Abstract: Rearrangements in MLL (MLL-r) are common within very young children with leukemia and affect the prognosis and treatment. Previous studies have suggested the use of the NG2 molecule as a marker for MLL-r but these studies were performed using a small number of infants. We analyzed 148 patients (all less than 24 months, 86 less than 12 months) from various centers in Brazil to determine the predictive power of NG2 within that cohort. We show that NG2 can be used for MLL-r prediction; however, proper staff training and standardized sampling procedures are essential when receiving samples from multiple centers as the accuracy of the prediction varies greatly on a per center basis.
Abstract: Resource-rich countries tend to have a higher incidence of childhood acute lymphoblastic leukemia (ALL), whereas lower rates are seen in more deprived countries. This study describes the incidence of childhood acute leukemia in Brazil, an upper middle-income country, based on data from 16 population-based cancer registries (PBCRs).
Abstract: The Brazilian Population-Based Cancer Registry (PBCR) was started in 1967; today there are 20 PBCRs in Brazil. We report the first descriptive analysis of the incidence of childhood cancer based on data from 14 PBCRs, corresponding to 15% of the child and adolescent population in Brazil. Data were obtained from registry databases, including information on population coverage and data quality indicators. The International Classification of Childhood Cancer was used. Age-adjusted rates were calculated by world population. Incidence by cancer registry, age, sex, and cancer type were calculated per 1,000,000 children. Age-adjusted rates per 1,000,000 children/adolescents ranged from 92 to 220 among the 14 PBCRs. The principal groups of cancers were leukemia, lymphoma and central nervous tumors. The median incidence rate of childhood cancer in the 14 PBCRs was 154.3 per million; children 1-4 years of age had the highest incidence rates. The Brazilian PBCRs provide important information about pediatric cancer incidence in an emerging country. The observed incidence rates of childhood leukemia were similar to previous reported rates, and the age-specific incidence rates of retinoblastoma (0-4 years of age) were higher than those for developed countries. These data can be used as baseline incidence rates of childhood and adolescent cancer in Brazil in future epidemiological studies.
Abstract: T-cell acute lymphoblastic leukemia (T-ALL) may affect children in very early age. However, the critical events leading to this brief latency is still unclear. We used standard methods to explore NOTCH1 mutations and other specific molecular markers in 15 early childhood T-ALL cases. Most of them consisted of immature differentiation subtype. Despite being found in a lower frequency than that described for overall pediatric T-ALL, NOTCH1 alterations were the most frequent ones. Other alterations included MLL(+) (n=4), SIL-TAL1(+) (n=3), FLT3 mutation (n=1) and HOX11L2(+) (n=1). Our results suggest that NOTCH1 and MLL abnormalities are primary leukemogenic hits in early T-ALL.
Abstract: Genetic aberrations involving the mixed lineage leukemia (MLL) gene are frequently diagnosed in infant acute lymphoblastic and acute myeloid leukemia. More than 60 fusion partner genes have been described at the molecular level, 31 of which have been characterized solely in infant leukemia cases. Here we describe a new MLL fusion partner gene, NEBL, which was identified in a case of acute myeloid leukemia in an infant. The chromosomal breakpoints of the MLL-NEBL and NEBL-MLL fusion genes were cloned by long-distance inverse polymerase chain reaction. The chromosomal breakpoints were located at 10p12, approximately 570 kb telomic of the MLLT10 (AF10) gene. AF10 and NEBL are localized in such close vicinity that they cannot be distinguished cytogenetically by G banding. Therefore, the combination of cytogenetic and independent molecular techniques such as long-distance inverse polymerase chain reaction are indispensable for the rapid identification and characterization of rare MLL rearrangements.
Abstract: PURPOSE To describe event-free survival (EFS) and toxicities in children with low-risk acute lymphoblastic leukemia (ALL) assigned to receive either continuous 6-mercaptopurine (6-MP) and weekly methotrexate (MTX) or intermittent 6-MP with intermediate-dose MTX, as maintenance treatment. PATIENTS AND METHODS Between October 1, 2000, and December 31, 2007, 635 patients with low-risk ALL were enrolled onto Brazilian Childhood Cooperative Group for ALL Treatment (GBTLI) ALL-99 protocol. Eligible children (n = 544) were randomly allocated to receive either continuous 6-MP/MTX (group 1, n = 272) or intermittent 6-MP (100 mg/m(2)/d for 10 days, with 11 days resting) and MTX (200 mg/m(2) every 3 weeks; group 2, n = 272). RESULTS The 5-year overall survival (OS) and EFS were 92.5% +/- 1.5% SE and 83.6% +/- 2.1% SE, respectively. According to maintenance regimen, the OS was 91.4% +/- 2.2% SE (group 1) and 93.6% +/- 2.1% SE (group 2; P = .28) and EFS 80.9% +/- 3.2% SE (group 1) and 86.5% +/- 2.8% SE (group 2; P = .089). Remarkably, the intermittent regimen led to significantly higher EFS among boys (85.7% v 74.9% SE; P = .027), while no difference was seen for girls (87.0% v 88.8% SE; P = .78). Toxic episodes were recorded in 226 and 237 children, respectively. Grade 3 to 4 toxic events for groups 1 and 2 were, respectively, 273 and 166 for hepatic dysfunction (P = .002), and 772 and 636 for hematologic episodes (P = .005). Deaths on maintenance were: seven (group 1) and one (group 2). CONCLUSION The intermittent use of 6-MP and MTX in maintenance is a less toxic regimen, with a trend toward better long-term EFS. Boys treated with the intermittent schedule had significantly better EFS.
Abstract: There is increasing evidence that miRNA and transcription factors interact in an instructive fashion in normal and malignant hematopoiesis. We explored the impact of TEL-AML1 (ETV6-RUNX1), the most common fusion protein in childhood leukemia, on miRNA expression and the leukemic phenotype. Using RNA interference, miRNA expression arrays, and quantitative polymerase chain reaction, we identified miRNA-494 and miRNA-320a to be up-regulated upon TEL-AML1 silencing independently of TEL expression. Chromatin immunoprecipitation analysis identified miRNA-494 as a direct miRNA target of the fusion protein TEL-AML1. Using bioinformatic analysis as well as functional luciferase experiments, we demonstrate that survivin is a target of the 2 miRNAs. miRNA-494 and miRNA-320a were introduced to the cells by transfection and survivin expression determined by Western blot analysis. These miRNAs blocked survivin expression and resulted in apoptosis in a similar manner as TEL-AML1 silencing by itself; this silencing was also shown to be Dicer-dependent. miRNAs-494 and -320a are expressed at lower levels in TEL-AML1+ leukemias compared with immunophenotype-matched nonTEL-AML1 acute lymphoblastic leukemia subtypes, and within TEL-AML1+ leukemias their expression is correlated to survivin levels. In summary our data suggest that TEL-AML1 might exert its antiapoptotic action at least in part by suppressing miRNA-494 and miRNA-320a, lowering their expression causing enhanced survivin expression.
Abstract: Acute leukemia is the most frequent cancer in children. Recently, a new hypothesis was proposed for the pathogenesis of childhood acute lymphoblastic leukemia (ALL). The so-called 'adrenal hypothesis' emphasized the role of endogenous cortisol in the etiology of B-cell precursor ALL. The incidence peak of ALL in children between 3 to 5 years of age has been well documented and is consistent with this view. The adrenal hypothesis proposes that the risk of childhood B-cell precursor ALL is reduced when early childhood infections induce qualitative and quantitative changes in the hypothalamus-pituitary-adrenal axis. It suggests that the increased plasma cortisol levels would be sufficient to eliminate all clonal leukemic cells originating during fetal life. Because Brazil is a continental and tropical country, the exposure to infections is diversified with endemic viral and regionally non-viral infections, with some characteristics that support the recent adrenal hypothesis. Here we discuss this new hypothesis in terms of data from epidemiological studies and the possible implications of the diversity of infections occurring in Brazilian children.
Abstract: Maternal exposure to dipyrone during pregnancy has been associated with risk of infant leukemia (IL). N-Acetyltransferase 2 (NAT2) enzyme acetylates dipyrone, resulting in a detoxified metabolite. We performed genotyping to identify the distribution of NAT2 polymorphisms in duo samples from mothers and children previously investigated in a case-controlled study of IL.
Abstract: Acute lymphoblastic leukemia (ALL) in infants is characterized by a high frequency of MLL gene rearrangements. By contrast, the t(12;21) ETV6-RUNX1 fusion gene is typically detected in children older than 2 years. In a series of Brazilian infant leukemia cases, however, four younger cases harbored ETV6-RUNX1, at ages 2, 3, 5, and 7 months. This finding could represent a unique model for delineating the additional genomic hits required to accelerate the emergence of a frank leukemia in these t(12;21)-positive cases. We applied a whole-genome copy number analysis with single-nucleotide polymorphism (SNP) arrays, comparing t(12;21) infants with older pediatric age groups. Recurrent deletions, including 9p21.3 (CDKN2A, CKDN2B, and MTAP), 11p13 (CD44), 12p13.2 (ETV6), and patient-specific abnormalities were identified. Although infant cases with t(12;21) did not display specific genetic abnormalities explaining the short latency to overt leukemia, the frequency of copy number abnormalities increased proportionally with age. This novel SNP array analysis in an extremely rare series of cases opens new ideas about the etiology of ETV6-RUNX1-positive ALL.
Abstract: Population-based cancer registries (PBCR) are important in cancer epidemiology as they provide the basis for monitoring cancer incidence. Childhood acute lymphoblastic leukemia (ALL) is said to have lower incidence in developing countries, which has implications for its pathogenesis, but there are few studies concerning the completeness of cancer registries in developing countries. This study analyzes the number of cases and incidence of childhood acute lymphoblastic leukemia in three different cities in Brazil and estimates underreporting cases and possible PBCR failures.
Abstract: SIL-TAL1 fusion gene and the ectopic expression of HOX11L2 are common molecular abnormalities in T-cell acute lymphoblastic leukemia (T-ALL). To verify their influence on outcome, we analyzed a Brazilian pediatric T-ALL series of cases. One hundred and ninety two children, age ranged 0-21 years old, were consecutively diagnosed and treated. Reverse transcriptase-polymerase chain reaction (RT-PCR) technique was used to identify the molecular alterations. Kaplan-Meyer method was applied to estimate overall survival. The most frequent maturation stage was T-IV (40.1%), and 30.7% of cases were CD10(+). SIL-TAL1(+) and HOX11L2(+) accounted for 26.7% and 10.3% of the cases, respectively. The overall survival (OS) was 74% in 80-month follow-up. HOX11L2(+) was not predictive factor for outcome. Considering patients younger than nine years-old, those with SIL-TAL1(+) presented a poorer outcome (p = 0.02). The results of this study suggest that in the Brazilian population only the presence of SIL-TAL1 can predict outcome in a restricted group of patients.
Abstract: Denaturing high-performance liquid chromatography (dHPLC) was developed to screen DNA variations by separating heteroduplex and homoduplex DNA fragments by ion-pair reverse-phase liquid chromatography. In this study, we have evaluated the dHPLC screening method and direct sequencing for the detection of GATA1 mutations in peripheral blood and bone marrow aspirates samples from children with Down syndrome (DS). Cases were ascertained consecutively as part of an epidemiological study of DS and hematological disorders in Brazil. A total of 130 samples corresponding to 115 children with DS were analysed using dHPLC and direct sequencing methods to detect mutations in GATA1 exons 2, 3 and 4 gene sequences. The overall detection rate of sequencing and dHPLC screening methods was similar. Twenty mutations were detected in exon 2 and one mutation in exon 3 (c.231_232 dupGT) sequences of acute megakaryoblastic leukemia and transient leukemia samples. Four GATA1 mutations were newly described [c.155C > G; c.156_178 del23 bp; c.29_30 del GG; c.182C > A and c.151A > T,c.153_162 del 10 bp). Out of four, three had single nucleotide change. In conclusion, our results indicate that dHPLC is an efficient and valuable tool for GATA1 mutational analysis.
Abstract: In this concise report, we describe the history and evolution of childhood acute leukemia studies in Brazil, and the application if key biomarkers for clinical trials and epidemiological studies over the past 8 years. Highlights of each ongoing study are summarized. A Brazilian network integrating hospitals and scientific institutions from all country regions has been established. This organization is made possible through informatics and computer networking, and the standardization of pathological reviews including immunophenotyping and molecular characterization of childhood leukemias. The unique characteristics of the Brazilian population combined with a large clinical and epidemiologic framework for patient ascertainment has enabled large-scale epidemiological studies on childhood leukemia in Brazil.
Abstract: Chromosomal rearrangements of the human MLL gene are associated with high-risk pediatric, adult and therapy-associated acute leukemias. These patients need to be identified, treated appropriately and minimal residual disease was monitored by quantitative PCR techniques. Genomic DNA was isolated from individual acute leukemia patients to identify and characterize chromosomal rearrangements involving the human MLL gene. A total of 760 MLL-rearranged biopsy samples obtained from 384 pediatric and 376 adult leukemia patients were characterized at the molecular level. The distribution of MLL breakpoints for clinical subtypes (acute lymphoblastic leukemia, acute myeloid leukemia, pediatric and adult) and fused translocation partner genes (TPGs) will be presented, including novel MLL fusion genes. Combined data of our study and recently published data revealed 104 different MLL rearrangements of which 64 TPGs are now characterized on the molecular level. Nine TPGs seem to be predominantly involved in genetic recombinations of MLL: AFF1/AF4, MLLT3/AF9, MLLT1/ENL, MLLT10/AF10, MLLT4/AF6, ELL, EPS15/AF1P, MLLT6/AF17 and SEPT6, respectively. Moreover, we describe for the first time the genetic network of reciprocal MLL gene fusions deriving from complex rearrangements.
Abstract: CD26/DPPIV (dipeptidil peptidase IV) displays an array of diverse functional properties, with a role in the development of several human cancers. This enzyme is found mainly anchored in the membrane of cells although it also has an enzymatically active plasma isoform. The regulation of biological activities of cytokines by DPP IV activity has a potential role in the homeostatic regulation of hematopoiesis. In this study, we analyzed the CD26 antigen cell membrane expression by flow cytometry and the DPPIV activity in plasma of patients of acute leukemia. The results showed that the plasma DPPIV activity is significantly higher in leukemia patients and could be 100% inhibited by Januvia (Merck Sharp & Dohme) a selective DPPIV inhibitor. Although CD26 expression on immune cells were not leukemia-dependent the analysis of the correlation between CD26 expression and the DPPIV plasma activity were statistically significant (p < 0.01) in acute lymphoid leukemia (B-ALL and T-ALL).
Abstract: Archived neonatal blood cards (Guthrie cards) from children who later contracted leukaemia and matched normal controls were assayed for adenovirus (AdV) C DNA content using two highly sensitive methods. In contrast to a previous report, AdV DNA was not detected at a higher frequency among neonates who later developed leukaemia, when compared with controls.
Abstract: The human T-cell lymphotropic virus type 1 (HTLV-1) was the first human retrovirus known as a direct causal agent of a malignant disease. The vertical route of HTLV transmission is the most frequent pathway of the virus contamination. This study was performed to determine the prevalence ratio of HTLV-1 infection among nursing women. From January 2004 to January 2005, blood samples from 1033 nursing mothers from ParaÃba, Brazil were evaluated for HTLV antibodies by ELISA and HTLV-1 viral particles confirmed by polymerase chain reaction (PCR). HTLV antibodies were detected in 7 women. The overall seroprevalence ratio was 0.68% and HTLV-1 viral sequences were confirmed by PCR in 2 women. These preliminary data suggest that HTLV screening should be introduced as a mandatory test before breastfeeding and breast milk donation in ParaÃba, Brazil. Additionally, counseling programs would help reduce the prevalence ratio of HTLV-1 infected individuals in this Brazilian region.
Abstract: In this paper, we compared the birth weight distribution among 201 infant leukaemia (IL) cases with that of 440 noncancer controls enrolled in Brazil in 1999-2005. Compared with the general population and the stratum 2500-2999 g as reference, IL cases weighing 3000-3999 g presented an odds ratio (OR) of 1.68 (95% CI: 1.03-2.76), and those of 4000 g or more, an OR of 2.28 (95% CI: 1.08-4.75), P trend<0.01. Using hospital-based controls, the OR for 4000 g or more, compared to 2500-2999 g, was 1.30 (95% CI: 1.02-1.43) after adjusting for confounders (gender, income, maternal age, pesticide and hormonal exposure during pregnancy). The results suggest that high birth weight is associated with increased risk of IL.
Abstract: Down syndrome (DS) is an important risk factor associated with acute leukemia (AL). The presence of polymorphisms that reduce 5,10-methylenetetrahydrofolate reductase (MTHFR) activity has been linked to the multifactorial leukemogenic process. The authors have conducted a study to test whether 677C-->T and/or 1298A-->C polymorphisms of MTHFR would play an additional role in susceptibility of acute myeloid leukemia (AML) in DS children. They also verified whether any polymorphism in the MTHFR gene was associated with the risk of DS. Genetic polymorphisms determination was carried out in 248 samples from healthy individuals as controls and a total of 115 DS children (65 without leukemia and 50 with AML). The present study failed to reveal any association between these polymorphisms and risk of AML in DS children. The data also indicate that MTHFR polymorphisms are not associated with risk of being a DS child.
Abstract: Infant leukemia (IL) is characterised by the presence of MLL rearrangements and a poor outcome. FLT3 gene is consistently highly expressed in MLL+ patients. To correlate the clinical aspects of IL with FLT3 sequence alterations, we have analysed 159 children included in the Brazilian Collaborative Study Group of Infant Acute Leukemia. FLT3-D835 mutations and FLT3-ITD were detected by PCR-RFLP assay and standard PCR amplification, respectively. Mean age at diagnosis was 11.3 months. Overall, 7.5% (ITDs n=6 and D835 n=6) of patients contained FLT3 mutations. FLT3 mutated cases exhibited significantly higher white blood cells (WBC) than wild-type patients (p=0.013). Median overall survival time was 9.2 months (SE 3.3, 95% CI 2.8-15.6). Variables with significant poorer outcomes were age<6 months (p=0.0043), MLL+ (p=0.0292), AML subtype (p=0.0008), high WBC (p=0.0179) and FLT3-D835 mutation (p=0.042). The concomitant presence of FLT3 and MLL abnormalities displayed the worst survival (p=0.0032). Cox regression analysis, with survival as endpoint, showed that leukemia subtype and WBC were independent prognostic factors. Although FLT3 mutations were not a frequent genetic abnormality in this cohort, they might be prognostically important in IL, but this will need to be confirmed in the analyses of larger patient cohorts.
Abstract: We developed a procedure for DNA extraction from small volumes of fixed cell suspensions previously prepared for conventional cytogenetic analysis. Good quality DNA was isolated with a fast and simple protocol using DNAzol reagent. This provided suitable DNA for various types of molecular analyses, including polymerase chain reaction, restriction fragment length polymorphism, denaturing high-performance liquid chromatography, and direct sequencing. This technique provides sufficient material for such test, which are important for diagnosis of neoplastic diseases in pediatric patients.
Abstract: Acute leukemia in early childhood is biologically and clinically distinct. The particular characteristics of this malignancy diagnosed during the first months of life have provided remarkable insights into the etiology of the disease. The pro-B, CD10 negative immunophenotype is typically found in infant acute leukemia, and the most common genetic alterations are the rearrangements of the MLL gene. In addition, the TEL/AML1 fusion gene is most frequently found in children older than 24 months. A molecular study on a Brazilian cohort (age range 0-23 months) has detected TEL/AML1+ve (N = 9), E2A/PBX1+ve (N = 4), PML/RARA+ve (N = 4), and AML1/ETO+ve (N = 2) cases. Undoubtedly, the great majority of genetic events occurring in these patients arise prenatally. The environmental exposure to damaging agents that give rise to genetic changes prenatally may be accurately determined in infants since the window of exposure is limited and known. Several studies have shown maternal exposures that may give rise to leukemogenic changes. The Brazilian Collaborative Study Group of Infant Acute Leukemia has found that mothers exposed to dipyrone, pesticides and hormones had an increased chance to give birth to babies with infant acute leukemia [OR = 1.48 (95%CI = 1.05-2.07), OR = 2.27 (95%CI = 1.56-3.31) and OR = 9.08 (95%CI = 2.95-27.96)], respectively. This review aims to summarize recent clues that have facilitated the elucidation of the biology of early childhood leukemias, with emphasis on infant acute leukemia in the Brazilian population.
Abstract: Methylenetetrahydrofolate reductase (MTHFR) is an essential enzyme in the metabolism of folate. The presence of polymorphisms that reduce the activity of MTHFR has been linked to the multifactor process of development of acute leukemia. A case control study was conducted on Brazilian children in different regions of the country with the aim of investigating the role of MTHFR C677T and A1298C polymorphisms as risk factors in the development of acute myeloid leukemia (AML). We used the polymerase chain reaction restriction fragment length polymorphism method to genotyping 182 AML and 315 healthy individuals. The genotype 677 CT was associated with decreased risk [odds ratio (OR), 0.37; confidence interval (CI) 95%, 0.14 - 0.92], whereas 1298 AC genotype was linked with an increased risk [OR, 2.90; CI 95%, 1.26 - 6.71] of developing AML in non-white children. Further epidemiological study is needed to unravel the complex multiple gene-environment interactions in the role of the AML leukemogenesis.
Abstract: Meta-analysis has become an important statistical tool in genetic association studies, since it may provide more powerful and precise estimates. However, meta-analytic studies are prone to several potential biases not only because the preferential publication of "positive'' studies but also due to difficulties in obtaining all relevant information during the study selection process. In this letter, we point out major problems in meta-analysis that may lead to biased conclusions, illustrating an empirical example of two recent meta-analyses on the relation between MTHFR polymorphisms and risk of acute lymphoblastic leukemia that, despite the similarity in statistical methods and period of study selection, provided partially conflicting results.
Abstract: The polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene are associated with leukemogenesis. In order to investigate the influence of two polymorphisms in the MTHFR gene, 677C>T and 1298A>C, on the risk of acute lymphoblastic leukemia (ALL) we performed a case-control study in children from different Brazilians' regions. Genotyping of 176 ALL and 199 unselected healthy subjects was performed using PCR-RFLP assay. There was no association between the 677C>T or 1298A>C and risk of ALL in total case-control sample. However, 677T allele was linked to a decrease risk of ALL [odds ratio (OR), 0.43; 95% confidence interval (CI), 0.22-0.86], whereas the 1298A>C polymorphism presents an elevated risk factor [OR, 2.01; 95% CI, 1.01-3.99] in non-White children. Our investigation provides interesting data concerning the opposite effect of A1298C polymorphisms, particularly in the light of relatively scarce data regarding the MTHFR role in leukemia susceptibility in different populations.
Abstract: We report the molecular and epidemiological characterization of 128 human T cell lymphotropic virus type 1 (HTLV-1) isolates from Brazilian patients with different clinical manifestations of the infection. Thirty-two percent of the patients were asymptomatic, 44% had HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and 23% had adult T cell leukemia/lymphoma (ATLL). Phylogenetic analysis performed using part of the LTR region of the viral genome revealed that all Brazilian isolates belonged to the Cosmopolitan subtype, with the following distribution within the Transcontinental subgroup: 81.6% within the Latin American cluster and 15.8% outside the Latin American cluster. Two isolates belonged to the Japanese subgroup. Molecular analysis of the tax region showed a high nucleotide similarity ( approximately 99%) with 41 prototype sequences, including the ATK-1 isolate. The mean number of nucleotide substitutions ranged from 1 to 8. Five specific nucleotide substitutions, C7401T, T7914C, C7920T, C7982T, and G8231A, were highly conserved among the Brazilian isolates (79.6%), with a frequency ranging from 81.6% to 100% in the sample group and from 18.4% to 24.1% in the prototypes used, suggesting the existence of a molecular signature. These changes were not correlated with a specific clinical status of the patients and could be a molecular characteristic of the HTLV-1 strains that circulate in Brazil.
Abstract: Chromosome abnormalities often occur prenatally in childhood leukemia, characterizing an early event in leukemogenesis. The majority of the abnormalities occurring in infants involve the MLL gene on chromosome band 11q23. We describe the molecular cytogenetic findings of 207 infant acute leukemia (IAL) cases included in the Brazilian Collaborative Study Group of Infant acute leukemia.
Abstract: Infant acute lymphoblastic leukemia (IALL) is characterized by mixed lineage leukemia (MLL) gene rearrangements, unique gene expression profiles, poor prognosis, and drug resistance. One exception is cytosine arabinoside (Ara-C) to which IALL cells seem to be more sensitive. We quantified mRNA expression of Ara-C key enzymes in leukemic lymphoblasts from 64 Brazilian ALL children, 15 of them presenting MLL gene rearrangement, and correlated it with clinical and biological features. The diagnosis was based on morphological criteria and immunophenotyping using monoclonal antibodies. MLL gene rearrangements were detected by conventional cytogenetic analysis, RT-PCR and/or fluorescence in situ hybridization. The DCK and HENT1 expression levels were determined by real-time quantitative PCR using SYBR Green I. Relative quantification was made by the standard curve method. The results were analyzed by Mann-Whitney and Fisher exact tests. A P value of <or=0.05 was considered to be statistically significant. DCK and HENT1 expression levels were significantly lower in children with MLL gene-rearranged ALL compared to children with MLL germ line ALL (P = 0.0003 and 0.03, respectively). Our results differ from previous ones concerning HENT1 mRNA expression that observed a higher expression level in MLL gene-rearranged leukemias. In conclusion, the expression of the genes related to Ara-C metabolism was lower in MLL-positive children in the sample studied, suggesting the presence of population differences in the expression profile of these genes especially for HENT1.
Abstract: It has been reported that somatic mutations in the X-linked GATA1 gene are present in hematological clonal disorders in children with Down syndrome (DS). We analyzed retrospective samples of DS children with acute myeloid leukemia, transient leukemia (TL), and myelodysplastic syndrome (MDS) to test whether the specificity of GATA1 mutations can be helpful in distinguishing these hematopoietic disorders. A total of 49 samples were subjected to GATA1 mutation screening by direct sequencing and denaturing polyacrylamide gel electrophoresis (PAGE). Mutations in exon 2 of GATA1 were detected in six of eight DS-AML M7 samples and in four of six DS-TL; no mutation was detected in 13 children with acute lymphoblastic leukemia (DS-ALL), 6 with DS-AML (M0, M2, and M5), 6 with DS-MDS and in 8 DS infants without hematological disorders and 2 children with AML M7 without DS. Blast cells proportion in the sample represented a critical aspect on the sensitivity of mutation detection in GATA1, and a combination of sequence analysis and PAGE is necessary to detect mutations when blast percentage is low. The absence of detected mutations in any of the DS-MDS cases raises the question whether MDS in DS children is an intermediate stage between TL and AML M7, as previously suggested.
Abstract: There is evidence supporting a role for 5-10 methylenetetrahydrofolate reductase (MTHFR) gene variants in acute lymphoblastic leukemia (ALL). To provide a more robust estimate of the effect of MTHFR polymorphisms on the risk of ALL, we did a meta-analysis to reevaluate the association between the two most commonly studied MTHFR polymorphisms (C677T and A1298C) and ALL risk. All case-control studies investigating an association between the C677T or A1298C polymorphisms and risk of ALL were included. We applied both fixed-effects and random-effects models to combine odds ratio (OR) and 95% confidence intervals (95% CI). Q-statistic was used to evaluate the homogeneity and both Egger and Begg-Mazumdar tests were used to assess publication bias. The meta-analysis of the C677T polymorphism and risk of childhood ALL included 13 studies with a total of 4,894 individuals. Under a fixed-effects model, the TT genotype failed to be associated with a statistically significant reduction of childhood ALL risk (TT versus CT + CC: OR, 0.88; 95% CI, 0.73-1.06; P = 0.18). However, individuals homozygous for the 677T allele exhibited a 2.2-fold decrease in risk of adult ALL (TT versus CT + CC: OR, 0.45; 95% CI, 0.26-0.77; P = 0.004). In both cases, no evidence of heterogeneity was observed. No association between the A1298C variant and susceptibility to both adult and childhood ALL was disclosed. Our findings support the proposal that the common genetic C677T polymorphism in the MTHFR contributes to the risk of adult ALL, but not to the childhood ALL susceptibility.
Abstract: Infant acute leukemia (IAL) has a unique profile characterized by the high incidence of translocations involving the MLL gene located at the 11q23 region. To test the potential role of intrauterine and perinatal factors linked to the risk of IAL development, a hospital-based case-control study was conducted in different cities of Brazil. A total of 202 children (ages 0-21 months) with newly diagnosed IAL was enrolled (1999-2005), and 440 age-matched controls were selected from the same hospitals wherein IAL cases were treated. A statistically significant association between maternal use of hormones during pregnancy and IAL was observed [odds ratio (OR), 8.76; 95% confidence interval (95% CI), 2.85-26.93] in a multivariable analysis. The association of certain exposures during pregnancy (hormones, dipyrone, metronidazole, and misoprostol) and MLL gene rearrangements was tested using a case-case approach. Despite the lack of statistical significance, the magnitude of the OR for maternal exposure to dipyrone (OR, 1.45; 95% CI, 0.75-2.86), metronidazole (OR, 1.72; 95% CI, 0.64-4.58), quinolones (OR, 2.25; 95% CI, 0.70-25.70), and hormones (OR, 1.88; 95% CI, 0.50-7.01) may suggest the occurrence of interactions between such maternal exposures during pregnancy and MLL rearrangements, yielding into IAL development. The strong and statistically significant association between IAL and estrogen exposure during pregnancy observed in this study deserves further investigation to investigate its role in intrauterine leukemogenesis.
Abstract: Transient myeloproliferative disorder is a form of self-limited leukemia that occurs almost exclusively in neonates with Down syndrome. The authors report an unusual case of a newborn without constitutional trisomy 21 who developed undifferentiated leukemia and subsequently achieved clinical and molecular remission without chemotherapy. Cytogenetics and molecular analysis have shown trisomy 21 and GATA1 mutation restricted to leukemic cells. G-to-T transversion was detected, which is predicted to result in a premature stop codon (c.119G>T; pGlu67X) in diagnosis samples. These findings emphasize that there must be a powerful interaction between GATA1 and trisomy 21 in leukemogenesis process.
Abstract: Malignancies arising from Natural Killer cells (NK) were described mainly comprising disorders related to large granular lymphocyte expansion. Clinical, morphological and immunophenotypic characteristics of myeloid/NK cell precursor acute leukemia (M/NK-AL) have been mainly described in adult patients. We identified nine children with M/NK-AL precursor cells in a series of 264 childhood acute leukemia diagnosed in our laboratory from consecutive referrals before treatment. CD34 +/-, CD13/33 +, CD11b +, a-MPO + and CD56 +, characterized these cases with TcR alphabeta and gammadelta negative cells. The differential diagnosis between subtypes of NK leukemia with those of lymphoid or myeloid origin in childhood raises the question regarding the pathogenesis and therapeutic implications of this rare entity in children.
Abstract: In developing countries, BL has a strong association with EBV infection during childhood. In South America, the data have shown an EBV association intermediate between that reported in the United States (30%) and that in equatorial Africa (95%). Early age at EBV infection and lower socioeconomic status have been related to increased EBV-associated BL in developing countries. In Brazil, there are not enough data on childhood BL related to EBV infection. Our aim was to evaluate the clinicopathologic features and EBV association of 44 children with NHL from the state of Rio de Janeiro, situated in the southeast of Brazil. EBV was detected using RNA in situ hybridization in 36 biopsy specimens. DNA from fresh tumor samples and from paraffin-embedded tissues of patients were analyzed by PCR, in which the first reaction included primers for an EBNA-2 common region while the nested reaction amplified the region discriminating between EBV types 1 and 2 in separate reactions. EBV was detected in 21 of 29 BLs (72%), and type 1 virus infected the majority of EBV-positive BLs (18/21). There was a trend for younger age in children with EBV-positive BL compared to EBV-negative BL (median age 4 compared to 6 years, respectively; p = 0.056). Our study confirmed that in the southeast of Brazil BL had an intermediate association with EBV. A higher rate of EBV-associated BL was described in the northeast of Brazil. These differences are probably related to regional socioeconomic status. In conclusion, our study suggests that early infection with EBV in the background of a low socioeconomic condition associated with other environmental factors could contribute to BL in Brazil.
Abstract: HTLV-I/II infection is present in all regions of Brazil, but its prevalence varies according to the geographical area, being higher in Bahia, Pernambuco and Pará. It has been estimated that Brazil has the highest absolute number of infected individuals in the world. Blood donors screening and research conducted with special groups (indigenous population of Brazil, IV drug users and pregnant women) are the major sources of information about these viruses in our Country. HTLV-I causes adult T cell leukemia/lymphoma (ATLL), HTLV associated myelopathy/tropical spastic paraparesis (HAM/TSP), HTLV associated uveitis (HAU), dermatological and immunological abnormalities. HTLV-II is not consistently associated with any disease. Diagnosis is established using screening (enzymatic assays, agglutination) and confirmatory (Western blot, PCR) tests. The viruses are transmitted by blood and contaminated needles, by sexual relations and from mother to child, especially by breast feeding. Prevention efforts should focus on education of positive blood donors, infected mothers and IV drug users.
Abstract: We report a new case of therapy-related acute myeloid leukemia in a child with Langerhans cell histiocytosis. This patient was previously treated with a protocol of multidrug chemotherapy, containing a relatively low dose of etoposide (total dose of 900/m(2)). Twenty-six months after the end of the therapy, the patient returned to the hospital with fever and anemia. The white blood cell count was 53 x 10(9)/L. The bone marrow examination showed massive infiltration with French-American-British acute myeloid leukemia classification M4 blast cells. The patient did not respond to an intensive treatment with high dose ARA-C and idarubicin. He died 6 months later. The cytogenetic abnormality of the blast cells was a t(11;11)(p13 -15;q23), that has not been described before in a secondary leukemia case.
Abstract: T-cell leukemia/lymphoma (T-c LL) associated with prior infection with HTLV-I is rarely described in children. We present herein, the clinical, morphological, and virologic features of T-c LL, which occurred in eight pediatric cases with similar features of ATLL described in adults. There were three girls and five boys with age ranging from 2 to 18 years. Lymphoadenopathy, hepatosplenomegaly and marked skin lesions were presented in all cases. Five patients had hypercalcemia. The diagnostic criteria of T-c LL were based on both morphological and immunophenotypical analyses characterized by T-cell markers positively. Seven cases were cCD3+, CD4/CD25+, whereas CD1a and TdT were negative in all cases tested. HTLV-I antibodies were detected in all cases. HTLV-I provirus integration of at least one provirus was seen in all cases tested by molecular analysis. Mother-to-child transmission of HTLV-I was demonstrated in six cases. Interestingly, a homozygous deletion in p16 gene locus was observed in all four cases studied, while exons 7 and 8 of p53 were deleted in one child. The deletion of the p16(INK4A)/p14(ARF) or mutation of p53, key regulatory protein of cell cycle checkpoint in G1/S progression, found in five of the eight pediatric patients suggests that in these cases genetic lesions associated with HTLV-I infection may predispose for an early onset of leukemia.
Abstract: The contribution of human T-cell lymphotropic virus (HTLV-I) DNA by PCR in CSF and the intrathecal synthesis of antibodies to HTLV-I by the antibody index (AI) to the diagnosis of HTLV-1-associated myelopathy (HAM)/tropical spastic paraparesis (TSP) were evaluated. Cases of spastic paraparesis compatible with HAM/TSP had increased AI for HTLV-I (60/73) and HTLV-I proviral sequences in CSF (25/27). Among 27 patients with other neurologic diseases, three had increased AI and another three had positive HTLV-I DNA in CSF. Thus, the combination of PCR for proviral DNA and AI for HTLV-I in CSF provides consistent criteria for the diagnosis of HAM/TSP.
Abstract: We studied the transmission routes of human T-cell lymphotropic virus type I (HTLV-I) within families of 82 Brazilian patients diagnosed with adult T-cell leukaemia/lymphoma (ATL). Diagnosis of ATL in 43 male and 39 female patients was based on clinical and laboratory criteria of T-cell malignancy and detection of HTLV-I monoclonal integration. Samples were tested for HTLV antibodies and infection was confirmed as HTLV-I by Western Blot and/or polymerase chain reaction (PCR) assays. Overall 26/37 (70%) of mothers, 24/37 (65%) of wives, 8/22 (36%) of husbands, 34/112 (30%) of siblings and 10/82 (12%) offspring were HTLV-I infected. In 11 ATL patients, mothers were repeatedly HTLV-I seronegative, but HTLV-I pol or tax sequences were detected in 2 out of 6 cases tested by PCR. ATL patients with seronegative mothers related the following risk factors for HTLV-I infection: 6 were breast-fed by surrogate mothers with unknown HTLV-I status, 4 had a sexually promiscuous behaviour and 1 had multiple blood transfusions at a young age. Familial aggregation of ATL and other HTLV-I associated diseases such as HTLV-I myelopathy (HAM/TSP) and or uveitis, ATL in sibling pairs or in multiple generations was seen in 9 families. There were 6 families with ATL and TSP sibling pairs. In 3 families at least one parent had died with lymphoma or presenting neurological diseases and 2 offspring with ATL. Further to the extent of vertical and horizontal transmission of HTLV-I infection within ATL families, our results demonstrate that mothers who provide surrogate breast-milk appear to be an important source of HTLV-I transmission and ATL development in Brazil.
Abstract: Infant acute leukemia (IAL) frequently involves breakage and recombination of the MLL gene with one of several potential partner genes. These gene fusions arise in utero and are similar to those found in leukemias secondary to chemotherapy with inhibitors of topoisomerase II (topo-II). This has led to the hypothesis that in utero exposures to chemicals may cause IAL via an effect on topo-II. We report a pilot case-control study of IAL across different countries and ethnic groups. Cases (n = 136) were population-based in most centers. Controls (n = 266) were selected from inpatients and outpatients at hospitals serving the same populations. MLL rearrangement status was derived by Southern blot analysis, and maternal exposure data were obtained by interviews using a structured questionnaire. Apart from the use of cigarettes and alcohol, very few mothers reported exposure to known topo-II inhibitors. Significant case-control differences were apparent for ingestion of several groups of drugs, including herbal medicines and drugs classified as "DNA-damaging," and for exposure to pesticides with the last two being largely attributable, respectively, to one nonsteroidal anti-inflammatory drug, dipyrone, and mosquitocidals (including Baygon). Elevated odds ratios were observed for MLL+ve (but not MLL-ve) leukemias (2.31 for DNA-damaging drugs, P = 0.03; 5.84 for dipyrone, P = 0.001; and 9.68 for mosquitocidals, P = 0.003). Although it is unclear at present whether these particular exposures operate via an effect on topo-II, the data suggest that specific chemical exposures of the fetus during pregnancy may cause MLL gene fusions. Given the widespread use of dipyrone, Baygon, and other carbamate-based insecticides in certain settings, confirmation of these apparent associations is urgently required.
Abstract: We analysed 67 samples from Brazilian children of diverse ethnic origins with acute lymphoblastic leukaemia (ALL) for the presence of the TEL-AML1 fusion gene transcripts using reverse transcription polymerase chain reaction (RT-PCR). All 12 positive cases (20% of the 60 B-cell precursor ALL) had common (CD10+) ALL with a mean age of 4 years (range 1-10 years). We conclude that the frequency, age, distribution and clinical features of the TEL-AML1 fusion gene-positive ALL is similar in the diverse ethnic backgrounds of the Brazilian children to that in other countries with predominantly white Caucasian or oriental ethnicity. Apparent exceptions to this generality are discussed.
Abstract: We present a rare case of adult T cell leukemia/lymphoma (ATL) in which leukemic T cells expressed CD4 and CD25 surface antigens and infiltrated mammary glands during clinical course of the disease. A 40-year-old male was admitted with long-standing skin lesions and leukocytosis. Peripheral blood lymphocytes were highly pleomorphic and presented CD2, CD4, CD25, CD38 membrane surface antigens. The patient proved to be seropositive for human T-cell lymphotropic virus type I (HTLV-I) antibodies. Monoclonal expansion of lymphoid cells integrated with HTLV-I genome was observed, and the diagnosis of ATL chronic type was made. He underwent a chemotherapy regimen, and skin lesions and leukocytosis improved markedly. He progressed with an indolent clinical course of ATL, when he was admitted with bilateral hyperplasia of breast, recurrent skin lesions, and leukocytosis. Breast biopsy revealed bilateral gynecomasty, extensive leukemic infiltration of typical ATL cells in the mammary glands, and the presence of mammary epithelial cells productively infected with HTLV-I. This is the first report describing invasion of the mammary tissue with HTLV-I-transformed T-cells and HTLV-I-associated breast disease.
Abstract: The authors measured human T-cell lymphotrophic virus type I (HTLV-I) proviral load and intrathecal synthesis of antibodies to HTLV-I in CSF of 13 Brazilian patients with tropical spastic paraparesis/ HTLV-I-associated myelopathy (HAM). The authors also measured HTLV-I proviral load in peripheral blood mononuclear cells of five of these patients and found that it was 10- to 100-fold higher than that in CSF cells. The combination of HTLV-I proviral load and intrathecal synthesis of antibodies to HTLV-I appears to be a useful marker of disease progression. Patients with high viral load and no intrathecal synthesis of antibodies to HTLV-I had more rapidly progressing, serious clinical disease.
Abstract: To determine whether a unique human T-lymphotropic virus type I (HTLV-I) transmission cohort containing multiple disease manifestations could be used to establish a relationship between tax gene sequence and HTLV disease expression.
Abstract: We describe 195 cases of adult T-cell leukemia/lymphoma (ATLL) reported to the national registry of T-cell malignancies in Brazil between 1994 and 1998. We compared the effect of demographic differences and clinical features of 150 consecutive ATLL cases in different regions of this diverse country. At diagnosis, the predominant clinical sub-type was the acute type (60%), followed by lymphoma (22%), chronic (10%) and smoldering (8%) types. Although we expected that different sub-types would be present in different regions, on the basis of immunogenetic factors determined by ethnicity, we did not demonstrate these differences. There were no significant differences among ATLL subtypes by age or gender. No ethnic group predominated in the total population of patients, but significant differences were noted when examining ethnic distribution by region. Reflecting the general population distribution, white patients were seen more often in São Paulo and black patients in Bahia, than in other regions. In most regions, cases were equally distributed between blacks and mulattos, except in Pernambuco, where blacks were less frequent. The main clinical features were lymphadenopathy, skin lesions, hypercalcemia and hepatomegaly. Fourteen patients (9%) suffered from HTLV-I-associated myelopathy (HAM/TSP), either at diagnosis or during follow-up of ATLL. All cases but one had antibodies to HTLV-I, with concordant results with ELISA, WB and PCR analyses. For the antibody-negative case, pol and tax gene sequences were present in tumor cells when subjected to PCR analyses. The prognosis was generally poor, suggesting that the disease in Brazil behaves in similar fashion regardless of ethnic or geographical differences.
Abstract: To clarify the seroprevalence of human T-cell lymphotropic virus type I (HTLV-I) among hematologic and cancer patients in the State of Rio de Janeiro, Brazil, we investigated sera from 2430 individuals from the following groups: 152 patients with T-cell diseases, 250 with B-cell disorders, 67 with myeloid leukemia, 41 with Hodgkin's disease, 351 with a history of multiple blood transfusions, 235 patients with solid tumors of different types, and 109 family members of HTLV-I-infected patients. Antibodies to HTLV-I were screened by enzyme-linked immunosorbent assay or particle agglutination assays (or both). Repeatedly reactive samples were tested by Western blot and polymerase chain reaction assay to differentiate HTLV-I from HTLV-II. We found an increased seroprevalence rate of HTLV-I among those with lymphoid malignancies, mainly in T-cell diseases (28.9%), and these results were important in characterizing 44 cases of adult T-cell leukemia/lymphoma. We confirmed the presence of HTLV-I and HTLV-II infections in blood donors (0.4% and 0.1%, respectively), in patients exposed to multiple blood transfusions (10.2% and 0.8%, respectively), and in 30 (27.5%) of 109 family members of HTLV-I- or HTLV-II-infected patients. We also confirmed the high rate occurrence of adult T-cell leukemia/lymphoma among lymphoproliferative disorders in Rio de Janeiro, Brazil.
Abstract: Acute leukemia has a high concordance rate in young identical twins and in infants this is known, from molecular analysis, to reflect an in utero origin in one twin followed by prenatal metastasis to the other twin via intraplacental anastomoses. The situation in older twins with leukemia has been less clear. We describe a pair of identical twins who were diagnosed with a T-cell malignancy at 9 and 11 years of age, one with T-cell non-Hodgkin's lymphoma and the other with T-cell acute lymphoblastic leukemia. Leukemic cells from the twins shared the same TCR beta gene rearrangement with an identical 11 bp N region. The most plausible interpretation of this result is that these malignancies were initiated in one twin fetus in utero, in a single T-lineage cell that had stable bi-allelic TCR beta rearrangements. Progeny of this cell then spread to the other twin before birth via shared placental vasculature. This was then followed by a 9- and 11-year preleukemic latent period before clinical disease manifestation as leukemia or lymphoma. This result has considerable implications for the etiology and natural history of pediatric leukemia.
Abstract: A patient with adult T-cell leukemia (ATL) characterized by a suppressor phenotype is reported. A 52-year-old mulatto male presented with symptoms and signs of hypercalcemia. His laboratory finding disclosed a peripheral blood specimen with abnormal cells characterized by a rather pleomorphic morphology and polylobated nucleous typical of ATL cells. Serum calcium and LDH were 18.2 mg/dl and 1373 IU, respectively. The phenotype of these cells was CD2+, CD4-, CD8+, CD28+ associated with the expression of activated antigens such as CD25, CD38, CD71 and CD30. Ki-67 positive were found in 20% of cells. The argyrophilic stain for nuclear organizer regions (AgNORs) was shown one cluster in 35% of abnormal cells. The serum antibodies were positive against human T-cell lymphotropic virus type I (HTLV-I) and clinical features were compatible with the diagnosis of ATL acute type. The combination therapy with cyclophosphamide, vincristine, prednisone decreased the number of leukemic cells but the clinical course was aggressive. He only responded transiently to treatment and died of multiorgan failure due to uncontrollable septicemia two weeks after admission.
Abstract: T-cell malignancies in Brazil have a high seroprevalence rate of HTLV-I antibodies. We have analyzed the disease features in 188 Brazilian patients with a T-cell disorder. These included 40 with T-lymphoblastic leukaemia or lymphoma (T-ALL/T-LbLy) and 148 with mature T-cell diseases: 5 T-prolymphocytic leukaemia, 53 adult T-cell leukaemia/lymphoma (ATLL), 54 cutaneous T-cell lymphomas, 29 pleomorphic T-cell lymphomas and 7 large granular lymphocyte leukaemia. The diagnosis was based on clinical, morphological and immunological features and HTLV-I serology. ATLL in Brazil has the same diseases features as in other endemic regions, the only apparent differences being: age, Brazilian patients being younger than Japanese, and ethnic grouping, one third of Brazilians being white Caucasians of European descent. We applied a scoring system based on the presence or absence of typical features associated with ATLL; hypercalcaemia, cell morphology, immunophenotype, histopathology and HTLV-I status, to see whether it may help in diagnosing cases of ATLL. All had high scores, whereas all other T-cell diseases scored low. Only 5 ATLL cases were HTLV-I-negative by serology, but they had otherwise typical features of ATLL, and their cells did not have HTLV-I proviral sequences by DNA analysis. Such cases suggest that ATLL may develop in a minority of individuals living in regions where it is endemic, without evidence of HTLV-I infection, and that other factors may contribute to the pathogenesis of the disease.
Abstract: A 64-year-old woman is reported with Stage I (Rai) chronic lymphocytic leukaemia (CLL), in whom hypercalcemia developed when an increased proportion of prolymphocytic cells characterized a transformation of CLL in prolymphocytoid leukaemia (CLL/PL). Although hypercalcemia is more frequently found in T-cell leukaemia associated with human T lymphotropic lymphocyte type I, scattered reports indicate that patients with B-CLL can also be affected with this metabolic disturbance. The case described here, progressed with an indolent course of CLL for 26 months, when she was admitted with a very aggressive disease characterized by a high WBC count, splenomegaly and hypercalcemia. Despite an effort to achieve a clinical remission, she failed treatment and death was attributed to unresponsive hypercalcemia. The mechanism of hypercalcemia in such cases is unclear as no parathyroid adenoma or second malignant tumor was found ante mortem. This electrolytic disturbance would appear to be a direct consequence of the transforming leukaemia and a possible mechanism involving a secreted humoral factor that could lead to altered calcium metabolism.
Abstract: Adult T-cell leukemia/lymphoma (ATL) is a malignancy that occurs most frequently in south-western Japan and the Caribbean basin. The primary etiologic agent for this disease, human T-lymphotropic virus type I (HTLV-I), is endemic in these areas. Only a small percentage of individuals infected with HTLV-I develop ATL. The factors that determine the development of malignant disease as an outcome of HTLV-I infection in an individual are unknown. ATL is histopathologically heterogeneous and firm diagnosis is made on the contribution of clinical, laboratory and histopathologic features. The wide variety of laboratory assays available to geographically diverse populations has led to a need to standardize the criteria for determining the diagnosis of this disease for epidemiologic studies. This report summarizes current information regarding ATL and proposes a classification facilitating comparison of case series in geographically and ethnically different populations.
Abstract: 1. CD44 is an adhesion molecule expressed by B and T lymphocytes that mediates cell attachment to extracellular matrix components and specific cell surface ligands. In normal process of T-cell development, CD44 can be implicated in homing of bone marrow-derived T-cell precursors into the thymus. In hematopoietic malignancies, CD44 and other adhesion molecules can mediate the behavior of neoplastic cells such as metastatic migration. In the leukemic process, CD44 expression is correlated with increased numbers of circulating blasts and it is present at other sites such as the central nervous system. 2. In the present study, CD44 was investigated in lymphoblasts from 30 patients with T-cell lymphoblastic leukemia (T-ALL) and in peripheral lymphocytes from 10 healthy individuals. CD44 expression was detected in 23 (77%) of T-ALL cases studied and was correlated with clinical features such as mediastinal mass, adenomegaly, and infiltration of the central nervous system and other organs. Interestingly, CD44 expression in patients with tumor infiltration was higher than in patients with no tumor infiltration. 3. These data suggest that CD44 may be regarded as an additional marker for tumor expansion in T-cell leukemias.
Abstract: The enzyme myeloperoxidase (MPO) is the most specific marker of myeloid lineage. The recognition of acute myeloid leukaemia (AML) with minimally differentiation (AML-M0) is established with methods that include myeloid markers CD13/CD33 and detection of MPO in blast cells by immunological techniques or electron microscopy cytochemistry (EM). We have analysed the presence of MPO in leukaemic blast cells by conventional cytochemistry and immunological methods using a monoclonal antibody anti-MPO (CLB-MPO1) in 121 cases of acute leukaemia. The aim of the study was to investigate the sensitivity of this McAb to identify AML-M0, as CD13/CD33 can be expressed in some cases of acute lymphoblastic leukaemia (ALL) and EM cytochemistry is not always available in many laboratories. Anti-MPO was positive in all cases of AML (M1-M5) which were positive by Sudan Black B reaction in similar or higher percentage ratio for each case, although in some of them did not label with CD13/CD33 tested by IF and IPc techniques. Based on the anti-MPO positivity, 5 out of 10 cases called undifferentiated leukaemia (AUL) were reclassified as AML-M0, though 4 cases were CD13/CD33 negative. Furthermore, after analysing the anti-MPO expression among 32 cases of ALL, we had to reclassify four of them as acute biphenotypic leukaemia. We conclude that anti-MPO is a very sensitive and reliable tool in AML diagnosis and has an important role in distinguishing minimally differentiated AML and biphenotypic acute leukaemia from AUL and ALL.
Abstract: Acute promyelocytic leukemia represents 5-10% of acute myeloid leukemia cases (AML) recorded in the literature, occurring more frequently in young adults. It has a special clinical and biological behaviour when compared to the other forms of AML, being characterized by a particular morphology of blast cells (M3 in FAB classification), translocation of chromosomes 15;17, and disseminated intravascular coagulation at diagnosis or after the onset of chemotherapy. Within this AML subgroup there are 2 morphological subsets called the hypergranular promyelocytic leukemia and the hypogranular or variant form. We have studied clinical and laboratory aspects of 19 cases of AML M3 out of 217 AML cases, and observed a high incidence of failure to recognize the M3 variant form, although its diagnosis has been mainly based on cytomorphology. Only 4 out of 8 cases of the variant form received in our laboratory were correctly diagnosed, being the other 4 cases wrongly identified as the myelomonocytic subset of AML (M4). Immunophenotyping with monoclonal antibodies using CD2 and CD7 as T cell markers, CD10 and CD19 as B cell markers and CD33, CD13, CD14, CD15 and anti MPO as myeloid markers is a complementary diagnostic tool that permits solving difficult cases. It is important to classify AML correctly because of the special therapeutic and prognostic features of AML M3, which differently from other AML forms, has been successfully treated with cellular differentiating agents.
Abstract: In order to characterize the clinical, cytogenetic, and outcome features of childhood acute megakaryoblastic leukemia (AMKL), we reviewed 24 cases; 14 were identified among 150 consecutive newly diagnosed acute myelogenous leukemia (AML) patients at St. Jude Children's Research Hospital, and 10 were cases referred to the National Institute of Cancer in Rio de Janeiro, Brazil. There were 5 Down syndrome patients and one patient with chronic myeloid leukemia (Ph+) in blastic crisis. Twelve patients had significant hepatosplenomegaly. Leukemic cell morphology and cytochemistry were consistent with the M7 classification in 17 cases, and all cases tested expressed megakaryocytic surface antigens. AMKL patients were significantly younger than other AML patients (P = 0.0001) and had poorer responses to therapy (P = 0.03, univariate analysis only). Ten of 24 failed induction, and only 5 are disease-free at 6 months to 4.5+ years. We conclude that AMKL usually affects young children, frequently producing marked organomegaly. It comprises approximately 10% of pediatric AML cases, and responds poorly to intensive AML therapies.
Abstract: A t(11;14)(p15;q11) was the sole chromosome abnormality observed in the malignant cells of a 10-year-old boy with acute leukemia. Morphologically, these cells were classified as L1 by the criteria of the French-American-British Working Group. Cytochemical analysis revealed that the leukemic cells were negative for Sudan Black B, periodic acid Schiff, and esterases, and positive for acid phosphatase. Immunophenotyping disclosed that the cells expressed a very immature antigenic profile [CD34+, CD7+, cytoplasmic CD3+, membrane CD3-, CD4-, and CD8-]. In spite of very intensive chemotherapy, complete remission was never induced, and the child died of progressive disease. The relationship of this case to other reported cases of acute leukemia arising from immature pluripotent hematopoietic cells is discussed.
Abstract: 1. Acute leukemias have been defined as major types of lymphoblastic and myeloblastic leukemias according to morphological and cytochemical criteria. 2. The technical improvements and standardization of immunofluorescence and immunocytology staining methods have provided new insights for classifying these disorders on the basis of monoclonal antibodies. 3. The scheme used to describe normal lymphoid and myeloid differentiation, when also used to describe their malignant counterparts, provides a well-established model for the immunological classification of acute leukemias. 4. In this review article, we suggest some guidelines for performing a series of cytochemical reactions using immunological markers to ensure a reliable diagnosis of acute leukemia.
Abstract: In a series of fourteen patients with adult T-cell lymphoma-leukaemia (ATLL) in Brazil the main features were lymphadenopathy, hepatosplenomegaly, hypercalcaemia, and high leucocyte counts, with abnormal lymphoid cells which had irregular nuclei. The series included the youngest patient with ATLL so far (18 months). Analysis with monoclonal antibodies showed a mature T-cell phenotype (CD4+, CD8-). Antibodies to HTLV-I and/or integration of HTLV-I proviral DNA were found in eleven patients. In the other three HTLV-I DNA could not be demonstrated even by means of the polymerase chain reaction; they therefore had HTLV-I-negative ATLL. This report of ATLL in Brazil corroborates serological reports that HTLV-I may be endemic in some parts of that country. Follow-up studies are required to identify precisely the main route of transmission of HTLV-I in South America and the risk factors for the development of ATLL in carriers.
Abstract: We describe the clinical and laboratory features of 17 adult patients with a variant form of hairy cell leukemia (HCL-V) studied over the last 7 years. The main findings were: splenomegaly, moderate anemia, thrombocytopenia, and a raised white blood cell count (median 116 x 10(9)/L; range 15 to 482). The circulating lymphoid cells had abundant villous cytoplasm and a round, occasionally bilobed nucleus, with a prominent nucleolus. Monocytopenia, a feature of typical HCL, was not seen; neither was tartrate-resistant acid phosphatase demonstrated in eight cases tested. HCL-V cells had a mature B-cell phenotype: CD19+, CD20+, CD22+, FMC7+, CD11c+, CD10-, CD5-, with light chain isotope restriction in 15 cases. In contrast to typical hairy cells, HCL-V cells were negative with the monoclonal antibodies anti-HC2 and anti-TAC (CD25). Immunoglobulin (Ig) was not detected in two cases and IgG was expressed in the cell membrane of 73% of cases. Bone marrow histology was different from HCL, showing interstitial infiltration by cells clumped together and a moderate amount of reticulin, but the spleen showed the typical red pulp expansion of HCL. HCL-V patients did not respond to splenectomy (5 of 7) or alpha-interferon (7 of 7); 2 of 3 patients had a partial response to 2'deoxycoformycin. The clinical course was benign with 15 patients alive with a median survival greater than 4 years. We confirm that HCL-V is a distinct clinico-pathologic entity with intermediate features between HCL and B-prolymphocytic leukemia.
Abstract: Sixteen patients presented with B cell leukaemia (white cell count 26-269 x 10(9)/l) which could not be classified as chronic lymphocytic (CLL), prolymphocytic leukaemia, or follicular lymphoma in leukaemic phase. Eleven patients (10 men, one woman) corresponded histologically to intermediate (INT) or mantle zone lymphoma, and five, with less well defined features, were designated small lymphocytic lymphoma with cleaved cells. The blood films showed a pleomorphic picture with lymphoid cells of predominantly medium size with nuclear irregularities and clefts. The membrane phenotype of the circulating cells showed strong immunoglobulin staining and reactivity with CD5 and FMC7 in all cases tested; CD10 was positive in six out of nine cases. The membrane phenotype of two of the five cases of small lymphocytic lymphoma was close to those of B-CLL and three resembled INT lymphoma. Bone marrow trephine biopsy specimens showed a diffuse pattern of infiltration in INT lymphoma. The median survival of these patients was less than two years, suggesting that a leukaemic presentation is associated with poor prognosis. By combining data from histology, membrane markers, and peripheral blood morphology, the leukaemic phase of typical INT lymphoma can be defined in most cases.
Abstract: The expression of two myeloid antigens identified by the monoclonal antibodies (McAb) MCS2 (CD13) and MY9 (CD33) was investigated in 136 cases of leukaemia. MCS2 was positive in blast cells of 78 of 88 (88.5%) and MY9 in 51 of 81 (64%) cases of acute myeloid leukaemia (AML) and chronic granulocytic leukaemia in myeloid blast crisis. One or other McAb, or both, were positive in all but 2 (2.3%) of these cases. MCS2 was more sensitive than MY9 to detect blasts of the myeloid lineage due to its most frequent reactivity in the cytoplasm of fixed cells by the immunoperoxidase (IP) technique compared with its membrane expression on cell suspensions by immunofluorescence (IF). MY9 was not suitable for tests on fixed cells. MCS2 was positive by IP but not by IF in 24% of AML, but the reverse was not observed. This suggests that the antigen detected by MCS2 is expressed in myeloblasts first in the cytoplasm and later on the cell membrane, pattern which is similar to that of the early antigens CD3 and CD22 in T and B lineage lymphoblasts, respectively. MCS2 was always positive in FAB types of AML-involving myeloblasts (M1-M4), including cases of undifferentiated morphology (M0), whilst MY9 was more frequently positive in monocytic leukaemia (M5). On the other hand, MCS2 was positive in 4 of 33 cases of acute lymphoblastic leukaemia and MY9 in 1. We conclude that both McAb, particularly MCS2, contribute to the better characterisation of myeloid leukaemias but that other tests are required to clarify the nature of the blasts when unexpected reactivities are observed.
Abstract: The morphology, membrane markers and ultrastructural cytochemistry of 39 cases of acute myeloid leukaemia (AML) with variable proportion (10-99%) of terminal deoxynucleotidyl transferase (TdT) positive blasts was compared with that of 134 cases of TdT negative AML. The incidence of TdT positive AML was 22.5% and this was significantly higher in poorly differentiated myeloblastic (M0 and M1) types (54%) than in all other FAB subtypes (10%; P less than 0.001). Our findings suggest heterogeneity among TdT positive cases. Whilst the majority correspond to genuine TdT positive AML in which evidence for exclusive myeloid nature was demonstrated by phenotypic, cytochemical and ultrastructural markers, a distinct minority (22%) of cases had mixtures of lymphoid and myeloid blasts. A change in phenotype occurred in three out of six cases studied in relapse. There was no difference in the incidence of immunoglobulin (Ig) gene rearrangement between TdT positive (two out of 12) and TdT negative (one out of 11) cases, although published data suggests that Ig gene rearrangement is significantly more common in TdT positive cases. The determination of TdT in AML allows the identification of cases of mixed acute leukaemia which probably represent proliferations of multipotent progenitor cells. The majority of TdT positive cases, nevertheless, correspond to immature types of myeloblastic leukaemia which may constitute a clinically distinct subgroup.
Abstract: The expression of antigens detected by monoclonal antibodies of the CD22 and CD3 groups was studied, by immunofluorescence (IF) on cell suspension and by immunoperoxidase (IP) on cells fixed on cytospin slides, in a range of B- and T-cell malignancies. CD22 was demonstrated in the B-cell leukemias more frequently by IP than by IF; in B-lineage acute lymphoblastic leukemia (ALL) it was positive only by IP. In chronic lymphocytic leukemia and lymphoplasmacytic tumors approximately 40% of cases were CD22 positive by IP but few by IF. In other disorders of mature B cells, CD22 was positive by both methods in most cases. CD3 was demonstrated by IP in all 48 cases of T-cell leukemia and lymphoma regardless of the maturation stage (i.e., from early thymic to mature T cells). This was not the case by IF, where only 16% of T-ALL and 73% of cases with postthymic T-cell leukemias were recorded as positive. The greater reactivity of CD3 and CD22 by IP reflect the early cytoplasmic expression of the antigens in immature T and B cells, respectively, as well as the possible greater sensitivity of the IP method. These differences should be taken into account when describing results in lymphoid malignancies. CD3 was not expressed in cells from any of the B-cell leukemias, and likewise, CD22 was not demonstrated in any of the T-cell disorders, confirming that both reagents are highly specific for their respective lineages.
Abstract: Ten patients with follicular lymphoma presented with a high white cell count (45-220 x 10(9)/l) which resembled chronic lymphocytic leukaemia (CCL): all had pronounced splenomegaly and, except one, generalised lymphadenopathy. The blood lymphocytes were small with scanty cytoplasm, densely condensed nuclear chromatin, and deep clefts originating in sharp angles from the nuclear surface. CLL cells are larger, have more cytoplasm, a different pattern of chromatin condensation, and may have shallow nuclear indentations or foldings rather than clefts. The circulating follicular lymphoma cells had moderate to strong membrane immunoglobulins (SmIg), low mouse (M)-rosettes, strong reactivity with the monoclonal antibody FMC7, and occasional expression of the CD5-antigen; at least one third of cells in each case were positive with anti-cALLa (J5,CD10). Half the cases were referred as B-CLL but none had the typical B-CLL immunophenotype: weak SmIg, M-rosettes of greater than 50%, CD5 positive, FMC7 and J5 negative. The diagnosis of follicular lymphoma was confirmed by lymph node biopsy in seven of the 10 cases. The overall response to treatment was poor and five patients died within three years of diagnosis. This aggressive form of follicular lymphoma needs to be distinguished from B-CLL as different management is required.
Abstract: A cytochemical study using: Sudan black B; alpha-naphthyl acetate (ANAE) staining; estimation of alpha-naphthyl butyrate (ANBE) esterase activity; acid phosphatase activity; and 5' nucleotidase activity was carried out in 15 cases of megakaryoblastic leukaemia. These included cases of M7 acute myeloid leukaemia and blast crises of chronic granulocytic leukaemia. The megakaryoblastic nature of the blasts was first established using two monoclonal antibodies against platelet glycoproteins, and by estimating the platelet/peroxidase reaction at ultrastructural level. Our findings suggest that megakaryoblasts have a typical cytochemical profile comprising positive ANAE staining and acid phosphatase activity with a predominant localisation in the Golgi zone and negative or weak ANBE activity. A similar positive cytochemical pattern was also found in five cases of erythroleukaemia (M6). The specificity of the 5'nucleotidase activity for megakaryoblasts was not confirmed. In most cases of megakaryoblastic leukaemia there was no 5'nucleotidase activity only two cases showed positive reactions--reactions were positive in several cases of myeloblastic and lymphoblastic leukaemia. We suggest that cytochemical methods may be useful in diagnosing M6 and M7 acute leukaemia because less than 40% of leukaemic cells react with specific monoclonal antibodies.
Abstract: An unusual case of 'pseudo-lymphoid' leukaemia is described. The leukaemic cells resembled small, mature lymphocytes but lacked B- and T-cell membrane markers as well as immunoglobulin (Ig) and T-cell receptor gene rearrangements. They showed, instead, features of early myeloid cells since they expressed 2 myeloid antigens, CDW13 and My9, and displayed peroxidase activity demonstrable by electron microscopy (EM) on unfixed cells. Cytogenetic studies showed monosomy 5, t(4;17) (p12;p11), t(2;3)(p23;q14) and an abnormal chromosome 12. Abnormalities of chromosomes 4 and 5 have been previously associated with 'pseudo-lymphoid' leukaemias. This case illustrates the value of sensitive methods for the characterization of blast cells and for the precise diagnosis of leukaemias with apparent 'lymphoid' morphology.
