Abstract: BACKGROUND: Residual proteinuria is a strong modifiable risk factor for renal failure progression. We previously showed that the antiproteinuric effect of combined half doses of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) is increased by raising diuretic dosage. Methods. We tested whether uptitration of loop diuretics on top of combined half doses of ACEI and ARB would better decrease proteinuria than uptitration to combined full doses of ACEI and ARB in a randomized, crossover, three periods of 6-week controlled study. Eighteen patients with stable proteinuria over 1 g/day with combined ramipril at 5 mg/day and valsartan at 80 mg/day in addition to conventional antihypertensive treatments were randomized to receive combined ramipril at 5 mg/day and valsartan at 80 mg/day, or combined ramipril at 10 mg/day and valsartan at 160 mg/day, or combined ramipril at 5 mg/day, valsartan at 80 mg/day and increased furosemide dosage in random order. The primary end point was the mean urinary protein/creatinine ratio in two 24-hour urine collections at the end of the three treatment periods. Secondary end points included mean 24-hour proteinuria, home systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP) and estimated glomerular filtration rate (eGFR) levels. RESULTS: The geometric mean urinary protein/creatinine ratio was lower with combined ramipril at 5 mg/day, valsartan at 80 mg/day and increased furosemide dosage compared to combined ramipril at 5 mg/day and valsartan at 80 mg/day, but also to combined ramipril at 10 mg/day and valsartan at 160 mg/day. These differences remained significant after adjustment for SBP, DBP or MAP and 24-hour natriuresis but not after adjustment on eGFR. Diuretic dosage uptitration did not increase the number of home systolic blood pressure measurements below 100 mmHg, but led to a statistically significant increase in the number of symptomatic hypotension episodes. CONCLUSIONS: A cautious uptitration of loop diuretic dosage in addition to combined half doses of ACEI and ARB better decrease proteinuria in patients with CKD and high residual proteinuria than uptitration to full dose of combined ACEI and ARB. This antiproteinuric effect of diuretics was partly explained by an eGFR decrease, suggesting the contribution of haemodynamic modifications, whose safety on the long term still need to be addressed.
Abstract: BACKGROUND: Placebo-controlled trials have found that angiotensin-converting enzyme inhibitors (ACEIs) decrease proteinuria and slow the progression of nondiabetic nephropathies. However, head-to-head comparisons of ACEIs and calcium channel blockers (CCBs) have shown conflicting results. Indeed, a recent metaanalysis concluded that there is still uncertainty about the greater renoprotection seen with ACEIs or angiotensin II receptor blockers in nondiabetic patients with renal disease, particularly when using true glomerular filtration rate (GFR) as the primary outcome. OBJECTIVE: The objective of this 3-year, randomized, multicenter, double-blind, placebo-controlled study was to compare true GFR decline (measured by yearly 51Cr-EDTA blood clearance) in nondiabetic, nonnephrotic adult hypertensive patients with estimated creatinine clearance of 20 to 60 mL/min.1.73 m(2), when randomized to a CCB (amlodipine, 5-10 mg/d) or an ACEI (enalapril, 5-20 mg/d). METHODS: Patients (aged 18-80 years) entered a 4-week placebo run-in washout period and previous antihypertensive drugs were tapered off over 2 weeks. Add-on treatments were atenolol (50-100 mg/d), loop diuretics (furosemide, 20-500 mg/d or torsemide, 5-200 mg/d), alpha-blockers (prazosin, 2.5-5 mg/d or doxazosin, 1-16 mg/d), and centrally acting drugs (rilmenidine, 1-2 mg/d or methyldopa, 250-500 mg/d). The primary end point was true GFR measured by yearly (51)Cr-EDTA blood clearance. Secondary end points included a clinical composite of renal events and tolerability collected by a full clinical and laboratory evaluation at each study visit. Post hoc analyses for the change in GFR, proteinuria, and time to clinical events were also planned on baseline proteinuria subgroups (<1 and >or=1 g/d) before unblinding the database. RESULTS: Three hundred eighteen patients entered the run-in period and 263 patients (156 men/107 women; mean age, 58 years) were randomized to receive either amlodipine (5 mg/d, n=132) or enalapril (5 mg/d, n=131). Blood pressure declined from 165/102 mm Hg to 138/84 mm Hg and 138/85 mm Hg with amlodipine and enalapril, respectively (no between-group significance). Only 20.8% of the patients randomized to ACEI treatment received diuretics at the last observation. No statistically significant difference was found between amlodipine and enalapril in GFR decline (-4.92 and -3.98 mL/min.1.73 m(2), respectively, at last observation) and composite secondary end point after a median follow-up of 2.9 years, including in the subgroup of patients with proteinuria >1 g/d at baseline. Protein excretion rate decreased significantly from baseline in patients taking enalapril plus diuretics (median -270 mg/d; P<0.001) but not in patients taking amlodipine plus diuretics (-25 mg/d at last observation). CONCLUSION: In this cohort of nondiabetic, nonnephrotic hypertensive patients, no statistically significant difference in true GFR decline was found over 3 years between amlodipine-treated patients and enalapril-treated patients with main add-on treatment with ss-blockers, including in the subgroup of patients with proteinuria >1 g/d.
Abstract: Despite repeated campaigns promoting transplantation, the high donation refusal rate remains unchanged. We targeted a well-educated population to assess the impact of our current transplantation promoting programs and personal feelings toward new approaches to organ donation. A questionnaire was proposed in five universities to students and university staffs that would have been likely to benefit from previous information campaigns in two South American and three European countries. All of the 2321 people interviewed replied to at least one question. Organ shortage was considered as a serious public health issue. However, there was a widespread ignorance of religious precepts concerning transplantation that contributed to the low acceptance rate of organ sharing after death. Financial rewards for donors or their families remain controversial. There was a general agreement for early educational programs in schools. Most people still consider organ donation as a gift, but many would now agree to readily share body parts after death. This biased population of well-educated people has still little knowledge of organ donation. The negative impact of ignorance surrounding religious precepts and the high acceptance rate of educational programs in schools, justify supporting an intensive international effort in education that should also include Church leaders.
Abstract: AIMS: We tested whether bone scintigraphy could help in the etiological diagnosis in patients with mild rhabdomyolysis, because different patterns of soft tissue radiotracer uptake have been found on bone scintigraphy in patients presenting with severe rhabdomyolysis, with a localized asymmetric pattern in traumatic lesions and a more diffuse and symmetric pattern in nontraumatic lesions. However, the performance of bone scintigraphy in mild rhabdomyolysis is unknown. The etiological diagnosis of rhabdomyolysis can be difficult, particularly in alcohol abusers who deny a recent alcoholic binge. MATERIAL AND METHODS: Bone scintigraphy was performed in 16 patients presenting with acute renal failure secondary to mild rhabdomyolysis (creatinine kinase levels < or =36,000 IU), with obvious causes in 10 cases and with uncertain etiologies in the remaining 6 patients. RESULTS: In 5 cases with evident traumatic rhabdomyolysis, and in 4 patients with uncertain etiologies, bone scintigraphy showed localized asymmetric soft tissue radiopharmaceutical uptake compatible with traumatic lesions. None of the 5 patients with nontraumatic rhabdomyolysis had significant soft tissue radiopharmaceutical uptake. In 1 patient with traumatic rhabdomyolysis, bone scintigraphy performed only 11 days after the initial insult was negative. One patient with an uncertain etiology also had a negative scintigraphy. CONCLUSIONS: Bone scintigraphy, when performed early in the course of the disease, may contribute to the etiological diagnosis of rhabdomyolysis if it shows asymmetric localized soft tissue radiopharmaceutical uptake compatible with traumatic lesions. However, bone scintigraphy is often negative in mild nontraumatic lesions.
Abstract: Crescentic glomerulonephritis are characterised by a crescent shaped cellular proliferation that may lead to glomerular destruction. Over 50% of at least 10 analysed glomeruli should be affected. The search for immune deposits by immunofluorescence is an important diagnostic step. Patients present with rapidly progressive glomerulonephritis (RPGN): renal failure, proteinuria and haematuria. Extra-renal symptoms may help diagnosis. Diseases are classified in three groups according to immunofluorescence studies. Group I is characterised by linear deposits along the glomerular basement membrane (GBM) with anti-GBM auto-antibodies responsible for Goodpasture's disease. Group II put together various diseases with immune complex deposits. In group III, no significant immune deposits are found. Those "pauci-immune" glomerulonephritis are secondary to anti-neutrophil cytoplasmic antibodies (ANCA) positive systemic vasculitis, mainly Wegener's granulomatosis and microscopic polyangiitis. Primary glomerulonephritis may also be associated with crescent formation. Treatment is urgently required. Diagnosis is suspected in the context of extra-renal symptoms or immunological abnormalities, and confirmed by a kidney biopsy, that also helps to define prognosis. Apart from some group II glomerulonephritis, the induction treatment is often an association of steroids and cyclophosphamide, with plasma exchange in case of Goodpasture's disease. After remission, a maintenance treatment is required for ANCA-positive vasculitis to prevent relapses. The high rate of opportunistic infections and cancer give the rational for searching less aggressive therapeutic options.
Abstract: Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and diuretics may exert synergistic antiproteinuric effects. Eighteen patients with a proteinuria >1 g/24 h after 6 mo of treatment with ramipril at 5 mg/d were assigned to receive in random order ramipril at 10 mg/d, valsartan at 160 mg/d, or combined ramipril at 5 mg/d and valsartan at 80 mg/d in addition to their antihypertensive treatment. The treatment periods lasted 4 wk and were separated by a 4-wk washout with ramipril at 5 mg/d. At the end of this crossover sequence, patients received combined ramipril at 5 mg/d, valsartan at 80 mg/d, and an increased furosemide dosage for an additional 4-wk period. The primary end point was the urinary protein/creatinine ratio for two 24-h urine collections at the end of each treatment period. No significant differences were noted between the study end points of the ramipril 10, valsartan 160, and combined ramipril 5 and valsartan 80 treatment groups. However, the urinary protein/creatinine ratio was lower with combined ramipril 5 and valsartan 80-increased furosemide dosage than with valsartan 160 and combined ramipril 5 and valsartan 80, with a similar tendency compared with ramipril 10. Combined ramipril 5 and valsartan 80-increased furosemide dosage decreased systolic home BP and increased serum creatinine but did not significantly increase the number of symptomatic hypotension cases compared with the other three treatments. Thus, in patients with severe proteinuria and hypertension, a cautious increase in diuretic dosage in addition to combined angiotensin-converting enzyme inhibitors and angiotensin receptor blockers decreases proteinuria and BP but may expose the patient to prerenal failure.
Abstract: BACKGROUND: The effect of furosemide on the survival and renal recovery of patients presenting with acute renal failure (ARF) is still debated. METHODS: Three hundred thirty-eight patients with ARF requiring dialysis therapy were randomly assigned to the administration of either furosemide (25 mg/kg/d intravenously or 35 mg/kg/d orally) or matched placebo, with stratification according to severity at presentation. The primary end point was survival. The secondary end point was number of dialysis sessions. Tertiary end points included time on dialysis therapy, time to achieve a serum creatinine level less than 2.26 mg/dL (<200 micromol/L), and time to reach a 2-L/d diuresis. RESULTS: There were no differences in survival and renal recovery rates between the 2 groups. Time to achieve a 2-L/d diuresis was shorter with furosemide (5.7 +/- 5.8 days) than placebo (7.8 +/- 6.8 days; P = 0.004). Overall, 148 patients achieved a urine output of at least 2 L/d during the study period (94 of 166 patients; 57%) with furosemide versus 54 of 164 patients (33%) with placebo ( P < 0.001). However, there were no significant differences in number of dialysis sessions and time on dialysis therapy between the furosemide and placebo groups, even in the subgroup of patients reaching a 2-L/d diuresis. CONCLUSION: High-dose furosemide helps maintain urinary output, but does not have an impact on the survival and renal recovery rate of patients with established ARF.
Abstract: We tested whether rat and human MPO have similar antigenic determinants using 36 human MPO-ANCA positive sera, one mouse anti-rat MPO and four mouse anti-human MPO monoclonal reagents. Purified rat and human MPO were used in ELISA, with or without crossinhibition by preincubation with human MPO or irrelevant antigen in the liquid phase. Only one human MPO ANCA positive serum exhibited significant binding in rat MPO ELISA. This binding was poorly inhibited by preincubation with human MPO in the liquid phase, but was conserved after adsorption of non specific anti-rat activity in a chromatography column. Three mouse anti-human MPO IgG monoclonal antibodies did not recognize rat MPO. Only one mouse anti-human MPO IgA monoclonal antibody bound to rat MPO. This binding was poorly inhibited by preincubation with human MPO (35% at 2 micro g/ml). Conversely, the mouse anti-rat MPO monoclonal did not bind human MPO. We have concluded that: (1) Most human MPO-ANCA recognize antigenic determinants on human MPO which are absent on rat MPO. Therefore, human auto-antibodies bind to epitopes which recently appeared after species evolution; (2) Inversely, the mouse anti-rat MPO monoclonal do not bind human MPO. Therefore, rat MPO epitopes have been altered during species evolution; (3) Mice injected with human MPO preferentially develop antibodies against xeno-epitopes which are not present in rodents. Therefore, human MPO may not be the best antigen to raise ANCA in animal models and (4) A comparison of the amino acid sequences of rat and human MPO may help elucidate the major antigenic epitopes.
Abstract: BACKGROUND/PURPOSE: Extracorporeal photochemotherapy (ECP) has been proposed for the treatment of various auto- and allo-immune reactions. However, a standard ECP regimen did not significantly alter the course of chronic progressive multiple sclerosis (MS). We tested whether an intensive ECP treatment can affect the course of secondary chronic progressive form of MS. METHODS: Five patients free of immunosuppression were included. Soluble 8-MOP was added ex vivo to a mononuclear cell suspension obtained in a cell separator. This cellular suspension was then irradiated using an UVA irradiator and re-infused into the patient. ECP was performed once a week for 6 weeks and then, depending on clinical evaluation, for a maximum of 6 months, with 2-year follow-up after treatment discontinuation. Scoring was performed with the Kurzke scale and EDSS by a single independent neurologist. RESULTS: One patient was excluded because of recurrent attacks at the very beginning of treatment. Four patients completed the study: one exhibited clinical improvement and three remained stable during the first 6 months of treatment. However, all experienced relapse or worsening of the disease after discontinuation of ECP treatment. CONCLUSION: Our intensive ECP treatment only transiently alters the course of the severe secondary chronic progressive form of MS, with rebound after treatment discontinuation.
Abstract: BACKGROUND/PURPOSE: The mechanism responsible for the beneficial effects of extracorporeal photochemotherapy (ECP) remains unknown. In the rat model of experimental allergic encephalomyelitis (EAE), the transfer of encephalitogenic cells (EAE cells) induces transient passive EAE, followed by resistance to subsequent disease induction through immunization with central nervous system antigens (active EAE). METHODS: We tested whether ECP exerts its therapeutic effect by inducing an immune response targeted on circulating pathogenic T-lymphocytes, which results from their increased immunogenicity. We compared the potential of untreated versus ECP-treated encephalitogenic cells to transfer passive EAE and protect against active induction of the disease. The UVA irradiation conditions were derived from intensive ECP protocols used in human clinical studies. RESULTS: Animals receiving untreated cells showed clinical symptoms following cell transfer but not after subsequent immunisation, whereas those receiving ECP-treated cells remained healthy following cell transfer but experienced clinical symptoms after subsequent immunisation. However, these symptoms were less marked than in control naive rats. CONCLUSION: Under these ECP protocol conditions, ECP-treated cells have no greater active stimulatory potential for the recipient immune system than untreated cells, since they are less effective at triggering the response that causes the resistant state to active EAE. We suggest that intensive ECP protocol may have deleterious effects with a risk of relapses after treatment discontinuation. The search for the irradiation threshold that would inhibit the T-cell pathogenic properties, but retain their ability to educate the immune system, remains a major research challenge.
Abstract: Antineutrophil cytoplasmic antibodies (ANCA) are present in sera from patients with various forms of vasculitis-associated glomerulonephritis. Because autoantibodies may be directed against antigens presented by apoptotic cells, generation of ANCA using apoptotic neutrophils (PMN) in syngenic Brown Norway (BN) rats was attempted. These rats are T-helper type 2-prone animals, already used successfully in other ANCA-positive animal models. BN rats received repeated injections of buffer or of nonapoptotic or apoptotic PMN aged in cultures, in the footpad and once intravenously. Four of five rats that received injections of PMN aged for 48 h developed ANCA, which cross-reacted with human leukocyte elastase in three cases. None of the rats that received injections of freshly isolated neutrophils developed ANCA. One rat that received buffer injection and that exhibited chronic skin infection developed delayed ANCA. None of the rats showed signs of disease: no weight loss and no proteinuria. Then a subnephritogenic dose of antibody directed against rat glomerular basement membrane was injected. Rats then were killed, and different organs were frozen and studied. No significant lesions were found in kidneys or lungs. It is concluded that injections of apoptotic but not freshly isolated PMN can generate ANCA in BN rats. Additional studies are needed to elucidate the immunization mechanism and the ability of these autoantibodies to initiate vasculitis in these experimental animals.
Abstract: BACKGROUND: ANCA are autoantibodies directed against polymorphonuclear cell antigens, mainly proteinase 3 (PR3) and myeloperoxidase (MPO), which are implicated in the pathogenesis of small-vessel necrotizing vasculitis. Alpha1-antitrypsin is the main inhibitor of neutral serine proteinase [i.e. human leukocyte elastase (HLE) and PR3] present in PMN alpha-granules (alphaGr). An association first reported by us between PR3 ANCA and the deficient PiZZ phenotype in ANCA-positive systemic vasculitis, now widely confirmed by others, led us to study the incidence and specificity of ANCA among PiZZ subjects. METHODS: We tested a population of 191 PiZZ (273 sera) for ANCA activity versus 272 PiMM matched control subjects using alphaGr or antigen-specific ELISA [PR3, HLE, MPO, lactoferin (LF) and bactericidal/ permeability increasing protein (BPI)]. RESULTS: The incidence of antibodies directed against alphaGr and HLE but not PR3, MPO, LF or BPI was increased in the PiZZ as compared to the PiMM group (Fisher probability respectively P < 0.0001 and P < 0.05). CONCLUSIONS: ANCA not directed against classical antigens (MPO and PR3) may be found in PiZZ patients. However, these patients do not develop systemic vasculitis features. Therefore, alpha1-antitrypsin deficiency is not sufficient to induce ANCA positive vasculitides, and may only act as a second hit amplifying factor.
Abstract: DIAGNOSIS OF RENAL INVOLVEMENT: The diagnosis of renal involvement in patients with Wegener's disease and microscopic polyangeitis is facilitated with the search for antineutrophil cytoplasmic autoantibodies (ANCA) but still requires biopsy for confirmation. TWO THERAPEUTIC PHASES: Induction should be initiated immediately, and generally leads to initial remission. Long-term treatment is then needed to reduce the risk of recurrence and relapse. FOLLOW-UP: Close monitoring of ANCA levels is important in these patients. Several protocols are currently under evaluation with the aim of limiting immunosuppression toxicity.
Abstract: RENAL INVOLVEMENT: Several types of vascularides without antineutrophil cytoplasmic autoantibodies (ANCA) can affect the kidney. The most frequently encountered are small-vessel vascularides leading to glomerulonephritis: Goodpasture's disease, lupus, and, most importantly, rheumatoid purpura and type II mixed cryoglobulinemia secondary to hepatitis C. Medium-sized vessel vascularitis, such as occurs in polyarthritis nodosa, is exceptional and leads to renal ischemia. Renal involvement in large-vessel vascularities is also exceptional, e.g. temporal artery arteritis and Takayasu's syndrome. THERAPY: Treatment must be adapted to the type of vascularides and also its class (small, medium, or large-vessel disease) and depends on the gravity of each individual patient's situation. A large range of treatments have been proposed, but there is little solid evidence concerning efficacy.
Abstract: OBJECTIVES: Alpha1-antitrypsin (alpha1-AT) is encoded by a highly polymorphic gene with over 75 codominantly expressed alleles at the protease inhibitor (Pi) locus classified as normal, deficient, dysfunctional or null. The aim of this study was to determine in patients with inflammatory bowel disease: (i) the prevalence of anti-neutrophil cytoplasmic auto-antibodies (ANCA) and their antigen specificities; (ii) alpha1-AT Pi phenotypes; and (iii) possible associations between ANCA, disease activity and deficient alpha1-AT alleles. DESIGN: Study of 95 consecutive patients with ulcerative colitis (UC) and 63 patients with Crohn's disease (CD). METHODS: Diagnosis and disease activity were determined by clinical, endoscopic and histological criteria. ANCA by indirect immunofluorescence (IIF) and Pi phenotyping by isoelectric focusing were performed for all patients. Positive IIF sera were tested in antigen-specific enzyme-linked immunosorbent assay: proteinase 3 (PR3), myeloperoxidase (MPO), lactoferrin (LF), lysozyme, human leucocyte elastase (HLE), cathepsin G and bactericidal/permeability increasing protein (BPI). RESULTS: Sixty-one patients with UC (64.2%) and only 11 with CD (17.5%) had ANCA (P < 0.001). Antigen specificities were PR3 (7/61), MPO (3/61), LF (6/61), HLE (1/63) and BPI (10/61) in UC, and PR3 (2/11) and BPI (2/11) in CD. Three PiZ alleles were found, matching the prevalence in the normal French control population. No relationship was found between the presence of ANCA, antibody specificity, disease activity and deficient alpha1-AT alleles. CONCLUSION: ANCA are more frequent in UC than CD and do not correlate with disease activity. ANCA and protease/antiprotease imbalance do not appear to modulate the clinical course of inflammatory bowel disease.
Abstract: Protein A immunoadsorption (IA) has proved effective in reducing proteinuria in patients with nephrotic syndrome after recurrence of focal and segmental glomerulosclerosis (FSGS) in kidney transplants. The effect of IA in nephrotic syndrome of other etiologies remains unknown. Nine patients with nephrotic syndrome secondary to membranous nephropathy (four cases), diabetes mellitus (one case), IgA nephropathy (two cases), and amyloidosis (two cases) had three to five IA of 2.5 plasma volumes over 4 to 8 d. Patients received no concomitant immunosuppressive treatment, and antihypertensive drugs were left unchanged. Proteinuria decreased from 12.64 +/- 5.49 to 3.35 +/- 2.2 g/24 h (mean +/- SD) in all patients after three to five IA. Hematocrit decreased from 37.32 to 32.64% (12.5% hemodilution) and serum albumin from 25.43 to 18.6 g/L (26.4% decrease). Proteinuria returned to baseline levels within 1 mo, as described in recurrent FSGS following transplantation. When serum albumin balance was controlled by albumin infusion after IA in two patients, comparable decreases in proteinuria were observed. Therefore, IA is effective in producing short-term reduction of proteinuria in nephrotic syndromes related not only to FSGS but also to membranous and IgA nephropathies, diabetes mellitus, and amyloidosis, which suggests that IA removes a nonspecific circulating hemodynamic-altering or permeability-increasing factor.
Abstract: Myeloperoxidase (MPO) is one of the main antigen targets of anti-neutrophil cytoplasmic antibodies (ANCA) in systemic vasculitides. It has been suggested that anti-MPO antibodies may recognize a single epitope on recombinant MPO. If confirmed on native MPO, this might allow specific therapeutic intervention with anti-idiotypic MoAbs to prevent antibody antigen interaction which is thought to cause activation of neutrophils and vasculitis. We searched for restriction in the epitope recognition profile in 50 patients with anti-MPO autoantibodies, using both native and recombinant MPO. Mouse monoclonals were purified and tested in competition assays. At least four epitopes were identified on native MPO using these monoclonals and only two were conserved on recombinant MPO. We found that human MPO autoantibody response was not restricted to a single epitope on native MPO, as all sera tested did not show the same profile in competitive studies with monoclonals. Furthermore, 30% of human anti-native MPO sera failed to recognize rMPO.
Abstract: We previously reported the presence of immunoglobulin A (IgA) antineutrophil cytoplasmic antibodies (ANCAs) in patients presenting IgA nephropathy (IgAN), particularly when associated with Henoch-Schonlein purpura. Most of the patients exhibited IgA ANCAs directed at an unknown 50-kd neutrophil protein but no IgG ANCAs. A subgroup of patients presented IgG as well as IgA ANCAs, suggesting an overlap syndrome between Henoch-Schonlein purpura and microscopic polyangiitis. We aimed at confirming the correlation of IgA ANCA titer with disease activity in a patient presenting IgAN relapse following kidney transplantation. The ANCAs were searched for by isotype- and antigen-specific enzyme-linked immunosorbent assay. Specificity was confirmed by antigen-specific enzyme-linked immunosorbent assay and Western blot analysis. At the onset of the disease in 1989, the patient presented with ANCAs of IgA and IgG class with specificity for myeloperoxidase and no rheumatoid factor. End-stage renal failure developed 1 year afterward. In 1991, he received a cadaveric renal allograft, and 9 months later developed acute nephrotic syndrome with rapidly progressive renal failure and recurrence of IgAN on the kidney transplant. An increase in IgA but not IgG ANCAs was found on clinical relapse after kidney transplantation. We conclude that rare patients may present an overlap syndrome between IgG ANCA-positive systemic vasculitis and IgAN, characterized by the presence of IgG and IgA anti-myeloperoxidase antibodies.
Abstract: The vasculitic lesions observed in Wegener's granulomatosis may be partly the consequence of proteases released following activation of neutrophils by ANCA. The activity of these proteases, including proteinase 3 (PR3) and elastase, is normally closely restricted to the inflammation site by a large excess of circulating alpha-1-antitrypsin (alpha1AT). Patients with ANCA-positive systemic vasculitis may exhibit a protease/antiprotease imbalance either genetically determined in the rare patients with deficient alpha1AT phenotypes, or more often acquired through both alpha1AT inactivation in various pathological conditions and possible inhibition of PR3/alpha1AT complexation by anti-PR3 ANCA. This imbalance may at least contribute to disease spreading or aggravation.
Abstract: BACKGROUND: Graft-versus-host disease (GVHD) is a major complication after bone marrow transplantation, which may be refractory to immunosuppressive drugs. As preliminary case reports suggested that extracorporeal photochemotherapy (ECP) using a Therakos device might be beneficial, we conducted a pilot study to assess the efficacy and safety of a new ECP method that does not require administration of 8-methoxypsoralen (8-MOP) to the patient. METHODS: ECP was performed three times a week for 3 weeks and then tapered according to the patient's course. Soluble 8-MOP was added ex vivo to an enriched mononuclear cell suspension obtained by a cell separator. This cellular suspension was then ultraviolet A irradiated and reinfused into the patient. Evaluation was performed using specific objective tests depending on clinical conditions. RESULTS: The two patients in the study with acute GVHD and severe liver dysfunction resistant to steroid pulse showed no improvement with ECP treatment. The five patients with chronic GVHD (c-GVHD) had the following clinical features: three patients had myositis and two patients had severe cutaneous c-GVHD, including one patient with sclerodermoid lesions, one with bronchiolitis obliterans, one with bronchitis, and one with liver involvement. Immunosuppressive drugs were either prohibited or ineffective. The number of procedures for each patient ranged from 13 to 30. Cytapheresis required the use of a double-lumen catheter (4/5) or an arteriovenous fistula (1/5). No side effects were related to 8-MOP or ultraviolet A irradiation. Four of five patients improved after ECP; one patient with bronchiolitis obliterans, a fibrotic condition, remained stable. CONCLUSIONS: ECP treatment may be helpful for the treatment of severe c-GVHD and the avoidance of increased immunosuppression.
Abstract: We studied the usefulness of monitoring antineutrophil cytoplasmic antibodies (ANCA) in chronic graft-versus-host disease (cGVHD), a major complication of allogeneic bone marrow transplantation. Antigen-specific ELISA and indirect immunofluorescence (IIF) were used to search for ANCA in 47 allogeneic bone marrow graft recipients who developed cGVHD and in 43 who did not (controls). Eight patients exhibited ANCA IIF positivity in the cGVHD group, but none in the controls. Specificity was confirmed in antigen-specific assays in only two cGVHD patients, both showing antilactoferrin (anti-LF) activity. One of these patients was followed-up, and the antilactoferrin antibodies were found only at the time of active but limited cGVHD. Among three ANCA IIF-positive patients, two had antinuclear autoantibodies and three antineutrophil alloantibodies secondary to blood transfusion, which may have been responsible for false ANCA IIF positivity. It is concluded that ANCA determination is not useful in patients with cGVHD. Polyclonal activation of B lymphocytes could result in ANCA activity during cGVHD. False-positive ANCA could be due to allo-immunization following blood transfusion. Rare patients may present antilactoferrin antibodies of unknown clinical significance.
Abstract: The american college of rheumatology (ACR) proposed in 1990 revised clinical criteria for systemic vasculitis classification to define homogeneous group of patients for clinical trials. However, microscopic polyarteritis (MPA) was not clearly identified from polyarteritis nodosa (PAN). Since anti-neutrophil cytoplasm antibodies (ANCA) are markers of disease activity of small vessel vasculitides including MPA, we tested the clinical significance of ANCA in 24 patients with PAN according to the ACR 1990 criteria. Two of 24 patients had ANCA, as defined by indirect immunofluorescence on normal human neutrophils, antigen-specific ELISA and Western blot analysis. However, they exhibited histologically proven small vessel but not medium vessel vasculitis. Furthermore, they had neither artery microaneurysms nor large organ injury consequent upon large vessel occlusion. Although they satisfied ACR criteria for PAN, they probably were misclassified and should be considered as MPA. We conclude that: (i) ANCA are not found in patients with classical PAN in the absence of MPA features; (ii) caution should be exercised when defining PAN according to the ACR 1990 criteria; (iii) ANCA may help systemic vasculitis classification.
Abstract: Circulating autoantibodies against the Goodpasture antigen (alpha 3 chain of type IV collagen) in the glomerular basement membrane (anti-GBM) and anti-neutrophil cytoplasm antibodies (ANCA) are each associated clinically with the development of a rapidly progressive glomerulonephritis. Antibodies with both these specificities coexist in a subset of patients, raising the possibility that they might be a result of cross-reactivity. In this study we have shown that 21% of patients with anti-GBM antibodies also had ANCA, and by using cross-inhibition assays, antigen-specific enzyme-linked immunosorbent assays, and Western blot analysis, these were shown to be two distinct populations of autoantibodies. In patients with both specificities, a greater proportion of the ANCA had specificity for myeloperoxidase (73.5%) than in patients with ANCA alone (36.6%). The presence of ANCA should be ascertained in all patients with anti-GBM disease as the prognosis for these double-positive patients may be dependent on both populations of antibodies.
Abstract: ANCA are associated with certain forms of systemic vasculitis, and have been reported previously to be of the IgG and IgM isotype. We examined the possible association between IgA ANCA and the IgA-related diseases Henoch-Schönlein purpura (HSP) and IgA nephropathy (IgAN). IgA and IgG ANCA were detected by isotype-specific solid-phase assays with a crude neutrophil extract, and their presence was confirmed by antigen-specific fluid-phase competitive inhibition tests and by indirect immunofluorescence. The possible interference by IgA rheumatoid factor was excluded. IgA ANCA were detected in sera from 11/14 HSP patients (79%), from 1/30 IgAN patients (3%), from 1/40 patients with vasculitides classically associated with IgG ANCA (2.5%), and in none of 60 sera from healthy blood donors. IgG ANCA were present with IgA ANCA in three patients with HSP. Only one HSP serum had anti-myeloperoxidase (MPO) activity by both IgA and IgG isotype-specific ELISA, and none was positive for proteinase 3 (PR3). Western blot analysis performed with neutrophil extract showed that the four strongest IgA ANCA-positive HSP sera reacted with a 51-kD protein; Western blot performed on cellular fractions showed that this protein is primarily membrane-associated, and different from fibronectin. Our study suggests that adult HSP is closely associated with circulating IgA ANCA, which may be directed against a different autoantigen than that recognized by IgG ANCA.
Abstract: Crescentic glomerulonephritis is usually classified into antiglomerular basement membrane (GBM) disease, immune-complex disease, or pauci-immune crescentic nephritis. The last category includes patients with systemic vasculitis as well as 'idiopathic' isolated crescentic nephritis. The presence of anti-neutrophil cytoplasmic antibodies (ANCA) in many patients with apparently isolated crescentic nephritis suggests that this represents a renal-limited form of vasculitis, and that truly 'idiopathic' crescentic nephritis is a very rare entity. We reviewed all renal biopsies with extracapillary proliferation seen at our centre since the availability of an ANCA assay (4-year period). There were 89 such biopsies of a total of 1240, of which 82 had sufficient details for further analysis. Of these, 10 had anti-GBM disease, 35 had epithelial proliferation associated with a variety of other diseases, and 36 had ANCA-associated disease. Nine of this last group had no extrarenal features and would previously have been classified as 'idiopathic' crescentic glomerulonephritis. The single remaining patient had an inactive glomerulonephritis with a scarred crescent; the predominant lesion was an interstitial nephritis. We therefore conclude that truly 'idiopathic' crescentic nephritis is very rare, if it exists at all. The ability to provide a practically complete classification of crescentic nephritis has important prognostic and therapeutic consequences.
Abstract: OBJECTIVE: To determine the prevalence of antineutrophil cytoplasmic antibodies (ANCA) in patients with active giant cell arteritis (GCA). METHODS: 23 patients with GCA were selected according to ACR 1990 criteria. Sera were harvested in all patients at an active stage of the disease and during followup (1 to 3 sera/patient for a total of 50 sera). ANCA positivity was searched for by indirect immunofluorescence (IIF) and enzyme linked immunosorbent assay (ELISA) using a neutrophil extract, and antigen specificity was determined by proteinase 3 (PR3), lactoferrin (LF) and myeloperoxidase (MPO) ELISA: RESULTS: Only 1/23 patients exhibited reactivity in IgG ANCA ELISA and IIF, with borderline anti-MPO reactivity in ELISA which was not inhibited by preincubation with MPO in the liquid phase, and no reactivity in Western blot analysis. Specificity could not be demonstrated in another patient who had positive IgG ANCA ELISA but negative ANCA IIF and negative antigen specific ELISA: All other patients were ANCA negative. CONCLUSION: As our patients with GCA did not exhibit typical ANCA when validated antigen specific assays were used, careful laboratory controls and clinical evaluation would seem essential in cases of apparent ANCA positivity.
Abstract: We aimed at confirming the antigen specificity recognized by anti-neutrophil cytoplasm antibodies (ANCA) in patients presenting systemic vasculitis with anti-myeloperoxidase (MPO) activity on ELISA. Thirty-five consecutive patients with reactivity in anti-MPO ELISA and systemic microscopic vasculitides were tested in slot and Western blot analyses. Eleven of 35 sera exhibited binding in Western blot studies with the MPO preparation used in the ELISA: five sera bound at the size of MPO, but five sera reacted with a 78 kD species (p78) co-purifying with MPO, and one serum blotted both MPO and p78. Sequence analysis and antigen-specific assays including Western blot studies showed that p78 is lactoferrin. All anti-lactoferrin positive sera, but no anti-MPO positive sera, also exhibited anti-nuclear binding on HEp2 cells with specificity for histone. We concluded that: (a) a subgroup of patients presenting systemic vasculitis with false anti-MPO reactivity on ELISA had anti-lactoferrin antibodies; (b) anti-lactoferrin was associated with anti-nuclear activity with specificity for histone; (c) these patients had systemic vasculitis without histological evidence of immune complex deposition.
Abstract: Three sets of experiments were performed to investigate the quality of myeloperoxidase (MPO) preparations and anti-MPO reagents. In the first experiment, two groups of three and four mice were immunized with commercially purified MPO (Calbiochem). Immunization was performed in PBS in the first group and in acetate buffer in the second. From the first group, five monoclonals were raised, and their specificities examined by ELISA and immunoblotting. Surprisingly, these antibodies reacted with lactoferrin (LF) and not MPO. In the second group, 13 monoclonals were raised; six of these reacted with MPO and seven reacted with LF. In a second set of experiments, MPO and LF reactivity were tested in different buffer conditions in the ELISA procedure. Slight variations in the detection of contaminating LF were found. In a third experiment, polyclonal reagents directed against MPO and LF were tested in MPO immunoblotting studies. A polyclonal anti-MPO reagent reacted not only with MPO but also with contaminating material including LF. The anti-MPO polyclonal reagent also reacted with LF on immunoblotting. We conclude that: (i) caution should be exercised when defining anti-neutrophil cytoplasm specificities of human sera and monoclonals by ELISA, (ii) the low concentration of contaminating LF in the commercially purified reference MPO preparation should be taken into consideration since it appears to have high immunoreactivity, (iii) changes in MPO immunoreactivity may occur under different buffer and pH conditions.
Abstract: ANCA and anti-GBM antibodies can occur together in RPGN. These patients are rare and have two distinct populations of antibodies and the ANCA specificity tends to be for myeloperoxidase more often than expected.
Abstract: We report the treatment of 5 patients with crescentic glomerulonephritis by immunoadsorption using a protein A column. Two had systemic vasculitis, 2 antiglomerular basement membrane disease and 1 systemic lupus erythematosus (SLE). In the patients with systemic vasculitis and SLE, there was successful removal of autoantibodies and rapid control of disease; remission was maintained over a mean follow-up of 2 years. Clinical improvement was not seen in 2 patients with anti-glomerular basement membrane (GBM) disease who presented with dialysis-dependent renal failure. There were no apparent clinical side-effects related to the immunoadsorption procedure. Protein A immunoadsorption offers a semiselective alternative to plasma exchange and appears to be safe and efficient in removing pathogenic autoantibodies in crescentic glomerulonephritis without anti-GBM antibodies.
Abstract: The presence of anti-idiotype antibody (anti-id) activity to anti-myeloperoxidase autoantibodies (anti-MPO) was measured by assessing binding of IgG in patients' sera to F(ab')2 fragments of polyclonal heterologous anti-MPO antiserum. Thirteen paired acute and remission sera and three groups of sequential sera from patients with systemic vasculitis were studied. The levels of anti-MPO fell as disease activity subsided with treatment. However, levels of anti-id activity against these anti-MPO rose as patients entered remission. This effect was still seen after controlling for binding to F(ab')2 constant regions and after polyethylene glycol precipitation of immune complexes. In the sequential studies, levels of anti-MPO and anti-MPO anti-id tended towards a reciprocal relationship. These observations point to dynamic interactions between autoantibody and complementary anti-idiotype antibodies in this system and a role for idiotypic networks in the regulation of anti-neutrophil cytoplasm antibodies.
Abstract: Thirty-five sera with binding greater than 20% in a myeloperoxidase (MPO, Calbiochem) ELISA were tested in Western blot analyses. 5/35 blotted MPO, but 5/35 blotted lactoferrin (LF) contaminating the commercial MPO preparation. All the anti-LF positive sera, but none of the anti-MPO positive sera, also exhibited anti-nuclear binding on Hep2 cells. Three of the patients with anti-LF antibodies had vasculitis affecting areas additional to the pulmonary-renal involvement which characterised the patients with anti-MPO antibodies.
Abstract: The association of ANCA isotype and affinity with disease expression is reviewed and new data on IgA ANCA levels and affinity in relation to disease activity are presented. Differences in the IgG ANCA subclass distribution exist between active disease and remission, with high affinity IgG3 ANCA present at the onset of disease. IgM ANCA, with or without associated IgG ANCA, correlates with pulmonary haemorrhage and disappears at remission. IgA ANCA are mainly found in patients presenting with Henoch-Schönlein purpura (HSP), and are directed against a distinct autoantigen of approximately 50 kD. The level and affinity of IgA ANCA also correlate with disease activity in HSP. Isotype as well as antibody specificity appear to be major determinants of disease expression.
Abstract: Necrotizing leucocytoclastic vasculitis is the histopathological hallmark of the small vessel systemic vasculitides (SV), a group of human diseases commonly associated with anti-neutrophil cytoplasm autoantibodies (ANCA). Necrotizing vasculitis is seen in a number of experimental systems, but none of these provide an ideal animal model for human SV. Vasculitis occurs in serum sickness reactions; in murine models of systemic lupus erythematosus; in association with infection, particularly chronic viral infections; and after treatment with certain drugs or inflammatory mediators. 'Spontaneous' vasculitis has been reported in specific mouse strains, especially with ageing, and in some larger species. The size of vessel involved and the type of inflammatory cells predominating are variable in these experimental situations, and none of these models feature antibodies analogous to ANCA. We have recently reported that Brown Norway rats treated with mercuric chloride (HgCl2) develop necrotizing leucocytoclastic vasculitis, especially in the gut, and also develop antibodies to myeloperoxidase (MPO) which recognize similar determinants on MPO to those bound by a subset of ANCA. Transfer of serum from HgCl2-treated rats to naive animals does not induce tissue injury. Preliminary experiments using pooled immunoglobulin or an anti-CD4 monoclonal antibody did not show useful therapeutic benefit from these treatments. HgCl2-induced vasculitis has weaknesses as an animal model of human SV, but is the only experimental model in which anti-MPO autoantibodies have so far been demonstrated, and therefore may be of particular relevance to ANCA-associated SV.
Abstract: Alpha 1-antitrypsin (alpha 1-AT) is the major inhibitor of proteinase 3 (PR3), the main target antigen of antineutrophil cytoplasm antibodies (ANCA) in Wegener's granulomatosis. alpha 1-AT is encoded by a polymorphic gene, with over 75 alleles, defining severely, medium and non-deficient protease inhibitor (PI) phenotypes. We describe the association of severely and medium deficient PI phenotypes with anti-PR3 positive systemic vasculitis, and postulate a pathogenetic role for alpha 1-AT deficiency and the occurrence of ANCA, with specificity for PR3 in a subgroup of patients with Wegener's granulomatosis.
Abstract: The presence of anti-idiotype antibodies (anti-id) to anti-neutrophil cytoplasm autoantibodies (ANCA) in intravenous immunoglobulin (IVIg) and remission sera from patients with systemic vasculitis, and the use of IVIg as an alternative therapeutic agent in open studies, has suggested a role for idiotypic regulation in the normal control of these disorders. Clinical benefit with IVIg has been reported in 15/16 patients, with sustained remission in eight. The ability of IVIg to produce lasting remission has been associated with a fall in ANCA levels and stimulation of endogenous immunoglobulin production. IVIg has the potential to influence the pathogenetic process in patients with vasculitis at several stages, and an influence on the idiotypic regulation of ANCA may explain the observed clinical responses and point to possible targets for more specific immunotherapy in the future.
Abstract: ANCA are markers for systemic vasculitis such as Wegener's granulomatosis (WG) and microscopic polyarteritis (MPA) and are usually of the IgG isotype. However, IgM ANCA may rarely occur in isolation, and in these circumstances, we have found that they are associated clinically with a syndrome of pulmonary hemorrhage and systemic vasculitis. How frequently IgM ANCA may occur in conjunction with IgG has not previously been investigated. We report here a study of 24 consecutive patients with IgG ANCA-positive systemic vasculitis (14 WG, 10 MPA) in whom we determined whether IgM ANCA occurred in association with IgG ANCA, and if so, whether this had clinical importance. Eight patients were found to have IgM ANCA as well as IgG ANCA, and of these, seven presented with severe pulmonary hemorrhage. None of the IgM ANCA-negative patients presented with pulmonary hemorrhage. Although the occurrence of pulmonary hemorrhage in ANCA positive vasculitis was closely correlated with the presence of IgM ANCA, the antigen specificity of these IgM autoantibodies was variable, since both myeloperoxidase (4 patients), PR3 (3 patients), and an unknown ANCA antigen (1 patient) were found to be targets. We conclude that knowledge of ANCA isotype may have important clinical and therapeutic implications for the management of patients with systemic vasculitis.
Abstract: BACKGROUND: Mercuric chloride (HgCl2) induces an autoimmune syndrome in Brown Norway (BN) rats characterized by the presence of a number of autoantibodies, including antibodies to glomerular basement membrane. Tissue injury has previously been reported to be rare in this model, but in the accompanying paper we describe changes in a number of organs including a necrotizing leucocytoclastic vasculitis in the gut. Myeloperoxidase (MPO) is one of the target antigens for anti-neutrophil cytoplasm antibodies, that are present in the majority of patients with the human autoimmune disease systemic vasculitis and have been implicated in pathogenesis. There is at present, no animal model for anti-neutrophil cytoplasm antibody positive systemic vasculitis. EXPERIMENTAL DESIGN: Ten BN rats were given five injections of HgCl2, each of 1 mg/kg, over 10 days. Sequential serum samples were tested for autoantibodies to MPO using solid phase assays, indirect immunofluorescence on normal rat neutrophils, and Western blot analysis. The specificity of these antibodies in the solid phase assay was confirmed by inhibition studies with purified antigen, and by testing binding to uncoated plates. Sera from control animals treated with saline were also tested. RESULTS: BN rats given HgCl2 developed antibodies to MPO, which in Western blots bound to similar determinants to those bound by human anti-MPO antibodies. The anti-MPO antibodies resolved spontaneously, with a time course similar to that of the anti-glomerular basement membrane antibodies, but there was no correlation between the two antibody responses in individual animals. There was no anti-MPO activity in sera taken before HgCl2 was given, nor in sera from saline-treated controls. CONCLUSIONS: BN rats treated with HgCl2 develop anti-MPO antibodies. Together with the description in the accompanying paper of necrotizing vasculitis in these animals, these observations suggest that HgCl2-induced autoimmunity in the BN rat may provide a useful model of anti-neutrophil cytoplasm antibody positive systemic vasculitis.
Abstract: Anti-neutrophil cytoplasm antibodies (ANCA) are markers of systemic vasculitis for which a pathogenetic role has been postulated. We have examined the effect of these autoantibodies on the function of normal human neutrophils in vitro. In the presence of ANCA positive sera luminol-amplified chemiluminescence was significantly increased compared to the values seen in the presence of normal or anti-double stranded DNA positive sera (P < 0.01). Five of six ANCA positive F(ab)2 preparations also produced significant neutrophil activation as demonstrated by the chemiluminescence response. This response was totally abrogated by the addition of neutrophil cytoplasm extract, containing the ANCA antigen. Addition of inhibitors to the chemiluminescence system demonstrated that the chemiluminescence response was inhibited by azide and salicylhydroxamic acid and reduced by histidine, suggesting that the chemiluminescence response was due to activation of myeloperoxidase, with generation of singlet oxygen. The chemotactic response to f-Met-Leu-Phe, a bacterial chemotactic peptide, was significantly augmented in the presence of ANCA. Chemotaxis to zymosan-activated serum and chemokinesis was not affected. Phagocytosis was also unaffected. We propose that neutrophil activation and modulation of neutrophil migration by ANCA may be of pathogenetic significance in systemic vasculitis.
Abstract: Strenuous physical exercise causes transient proteinuria and renal hemodynamic changes: decrease of renal blood flow and to a lesser extent of the glomerular filtration rate, and an increase of the filtration fraction. However, the mechanisms of these modifications are still poorly understood. In order to elucidate them we performed maximal exercise tests on 8 untrained healthy volunteers after inhibition of the renin-angiotensin system (RAS) by captopril, the sympathetic nervous system by a beta-blocking drug (acebutolol) or an alpha-blocking drug (prazosin) and the prostaglandin system by indomethacin. Urinary albumin excretion was measured in every subject first at rest (AB) and then after exercise (AA) performed successively without and with blockade by each of theses drugs. AA-AB difference in the captopril test (12.04 +/- 6.11 micrograms/min) compared to that in the control test (68.91 +/- 25.18 micrograms/min) was significantly reduced (p less than 0.02). This difference remained unchanged after acebutolol (59.87 +/- 21.91 micrograms/min, p = 0.62), prazosin (35.23 +/- 27.80 micrograms/min, p = 0.21) and indomethacin (55.21 +/- 28.43 micrograms/min, p = 0.35). There was a negative correlation between the lowering of AA elevation and the rise in plasma renin activity in the captopril test (r = 0.64; p less than 0.03). Only acebutolol decreased systolic blood pressure significantly. These results suggest that the RAS plays a major role in postexercise proteinuria. We hypothesize that stimulation of this system induces an increase of efferent glomerular artery constriction and consequently of glomerular transcapillary pressure and the filtration fraction. Captopril seems able to prevent these hemodynamic changes.
Abstract: Circulating IgG autoantibodies to myeloperoxidase (MPO) are associated with renal vasculitis and have been implicated in its pathogenesis. However, raised levels of these autoantibodies may persist during clinical remission. We tested whether this paradox could be explained by immunoglobulin subclass switching during disease evolution, since different subclasses have different immunological and biochemical properties. Sera with anti-myeloperoxidase (anti-MPO) activity from 33 patients with active disease and 20 anti-MPO positive follow-up sera were studied by an ELISA using a panel of anti-human IgG subclass monoclonal reagents previously calibrated on human myeloma proteins. Anti-MPO subclass distribution in initial sera was: IgG1, 31 (94%); IgG2, 10 (30%); IgG3, 24 (73%); and IgG4, 22 (67%). IgG3 anti-MPO decreased during follow-up (P less than 0.02), with no change in IgG1 and IgG4. Relative functional affinity of anti-MPO antibodies in purified IgG subclasses was studied by the diethylamine method. IgG3 fractions consistently had a greater affinity for MPO than the other subclasses. Sequential studies in four patients demonstrated an affinity maturation for IgG1 and IgG4 anti-MPO as IgG3 anti-MPO disappeared. We conclude that dynamic changes of subclass distribution and affinity may explain discrepancies between anti-MPO antibody titre and disease expression.
Abstract: Anti-neutrophil cytoplasm antibodies (ANCA) are specific markers for systemic vasculitis. In view of the autoreactivity to other autoantigens reported in patients with monoclonal immunoglobulins (MIg), the reactivity of 150 sera from 125 patients with MIg was tested for ANCA by radioimmunoassay (RIA) with inhibition stage and indirect immunofluorescence (IIF). Seven were positive for IgG ANCA, all with IgG MIg and 5 were positive for IgM ANCA, 4 with IgM MIg and 1 with IgG MIg. No IgA ANCA were found. The patterns seen on IIF were identical to those seen with sera from patients with systemic vasculitis and were cytoplasmic in 6 and peri-nuclear in 6. The restriction of the ANCA activity to the MIg was studied in six sera by light chain specific RIA, and anion exchange fractionation of the sera. The ANCA activity appeared to be polyclonal in at least three sera and could be found in the monoclonal fraction in only three patients. Associated autoimmune diseases were found in some of these ANCA positive patients including Sjögren's syndrome, MacDuffie hypocomplementemic vasculitis and rheumatoid polyarthritis but the classical vasculitic features normally associated with ANCA were not observed. We conclude that ANCA is a further autoreactivity present in some sera with MIg and discuss the relation between monoclonal gammopathies and autoimmunity.
