ANCA in diseases other than systemic vasculitis

Clinical implications of ANCA positivity in a hospital setting: a tertiary center experience

ANCA testing plays an established critical role in the diagnosis of ANCA Associated vasculitis (AAV). The spectrum of diseases associated with positive ANCA has recently broadened, thus calling into question the diagnostic implications of ANCA positivity in a hospital setting. We retrospectively studied all adult patients who had a positive ANCA test (by Indirect Immunofluorescence (IIF), ELISA or both) performed over the span of 19 years. Subjects were then divided into discordant (positive on one assay) and concordant ANCA (positive on both assays) groups based on their ANCA positivity status. The two groups were then compared with regards to their demographic, clinical and laboratory characteristics, the indication for ANCA testing in both groups and their final diagnoses. Of the 9189 ANCA tests ordered during the 19-year span of the study, 389 (4.2%) were positive. Two hundred and forty subjects met the exclusion criteria (patients aged less than 18 years or the lack of clinical and laboratory data in the medical file) thus resulting in a final cohort of 149 subjects. Of them, 122 subjects had discrepant ANCA results and 27 had matching ANCA results. Most cases in the discrepancy group were IIF positive and ELISA negative (86.8%). The diagnosis of AAV was highly unlikely in cases with discrepant IIF and ELISA serologies compared to cases with matching IIF and ELISA serologies (4.1% versus 44.4%, p value < 0.001). The diagnosis of AAV in unlikely in subjects with discrepancies between IIF and ELISA, particularly with only positive IIF.

Glomerular disease in patients with infectious processes developing antineutrophil cytoplasmic antibodies

To identify differences in treatment and outcome of various types of glomerulonephritis developing in the course of infections triggering antineutrophil cytoplasmic antibody (ANCA) formation, we analyzed published reports of 50 patients. Immunosuppressives were added to antibiotics in 22 of 23 patients with pauci-immune glomerulonephritis. Improvement was noted in 85% of 20 patients with information on outcomes. Death rate was 13%. Corticosteroids were added to antibiotics in about 50% of 19 patients with postinfectious glomerulonephritis. Improvement rate was 74%, and death rate was 26%. Two patients with mixed histological features were analyzed under both pauci-immune and post-infectious glomerulonephritis categories. In 9 patients with other renal histology, treatment consisted of antibiotics alone (7 patients), antibiotics plus immunosuppressives (1 patient), or immunosuppressives alone (1 patient). Improvement rate was 67%, permanent renal failure rate was 22%, and death rate was 11%. One patient with antiglomerular basement disease glomerulonephritis required maintenance hemodialysis. Glomerulonephritis developing in patients who became ANCA-positive during the course of an infection is associated with significant mortality. The histological type of the glomerulonephritis guides the choice of treatment. Pauci-immune glomerulonephritis is usually treated with addition of immunosuppressives to antibiotics.

Diagnostic and pathogenetic role of antineutrophil cytoplasmic autoantibodies

Anti-neutrophil cytoplasmic antibodies (ANCA) are mostly known as a useful diagnostic tool in patients with small-vessel vasculitides. With the accumulating knowledge of these autoantibodies, however, it becomes clear that the role of ANCA may not be only limited to a diagnosis of such disorders. The current review addresses, in addition to classical diagnostic associations, other diseases connected with ANCA positivity, both in adults and in children. The etiology of ANCA remains unknown, but still, the importance of both genetic and environmental factors is undoubted. The role of infection and chemicals in the etiology of ANCA-associated diseases is stressed in particular. A pathogenetic role of ANCA is suggested because of clinical observations based on the correlation of the vasculitis activity and the titer of ANCA. Many experiments show the effects of ANCA in various steps of an inflammatory process, particularly on leukocyte microbicidal activity and oxidative burst. Recent findings are analyzed in the experimental field and they are correlated with clinical significance.

Histological diversity of vasculitic lesions in MPO-ANCA-positive autopsy cases

To investigate the variety of histological features of vasculitic lesions in myeloperoxidase-specific antineutrophil cytoplasmic antibody (pANCA)-related vasculitis, retrospective pathological analysis was done on 13 autopsy cases, collected from 1990 to 1998 at five hospitals. These cases were classified into three groups: (i) pulmonary-renal syndrome characterized by capillaritis of lung and glomeruli with occasional small-vessel arteritis and/or phlebitis; (ii) glomerular capillaritis without pulmonary involvement associated with significant small-vessel arteritis; and (iii) extensive distribution of small-vessel arteritis with no capillary involvement. The results suggest that pANCA-related vasculitis encompasses a wide variety of vasculitic syndromes, including pulmonary-renal syndrome, microscopic polyarteritis nodosa, and classic polyarteritis nodosa. pANCA may contribute to pathogenesis in all of these cases.

Autoantibodies to molecular targets in neutrophils in patients with ulcerative colitis

Autoantibodies against neutrophil granulocytes are frequently observed in patients with ulcerative colitis, but a precise description of the autoantigens involved is lacking. Therefore, sera from 75 patients with ulcerative colitis were studied for antibody specificities by means of indirect immunofluorescence microscopy, enzyme-linked immunosorbent assays, and immunoblotting of extracts of neutrophils, neutrophil granules and lymphocytes. Fifty-six percent of the sera reacted in indirect immunofluorescence with ethanol-fixed neutrophils. On formalin-fixed cells most sera shifted fluorescence pattern, indicating a cytoplasmic origin of antigen(s). Only a few sera reacted with specific, known antigens. Immunoblots showed reactions with a broad panel of antigens with preferences for proteins around 55-65 kDa, which were present in azurophilic granules and in cytosol, an 80-kDa protein found in the specific granules, and a 110-kDa unknown cytosol component. In conclusion, neutrophil-specific IgG autoantibodies from ulcerative colitis patients react with several different antigens, most of which are of nonnuclear origin.

Clinical spectrum associated with positive ANCA titres in 94 consecutive patients: is there a relation with PR-3 negative c-ANCA and hypergammaglobulinaemia?

OBJECTIVE

To calculate the positive predictive value (ppv) of cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCAs) and anti-proteinase 3 (PR 3) antibodies for Wegener's granulomatosis (WG) and to evaluate their association with other diseases.

METHODS

The clinical files of all 94 patients who had a positive c- or perinuclear (p)-ANCA test, or both, in the laboratory of the University Hospital, Leuven between April 1995 and March 1996 and who attended the Internal Medicine Department of the hospital were retrospectively studied.

RESULTS

Of the 94 patients with ANCAs (fluorescence titre > or = 1/40), 57 were c-ANCA positive and 45 p-ANCA positive (eight were simultaneously c- and p-ANCA positive). Of the 57 c-ANCA positive patients, 23 had WG. The ppv for WG thus was 40%. This value did not increase by defining a higher threshold for a positive ANCA. There was not a good relation between ANCA titres and disease activity in the WG patients, nor was there a relation between anti-PR 3 antibody levels and WG disease activity. The ppv of anti-PR 3 antibodies for WG however was very high (85%). There was a positive correlation between the level of (hyper) gammaglobulinaemia and c-ANCA titres in those patients with final diagnoses not known to be associated with c-ANCA. Forty five patients had positive p-ANCAs. The largest group were those with inflammatory bowel disease (n = 20, of whom the majority had colitis ulcerosa or primary sclerosing cholangitis, or both); the great majority of these patients had no anti-myeloperoxidase antibodies. Vasculitis was present in eight patients, of whom two had WG (both were also c-ANCA positive).

CONCLUSION

There is a low ppv of c-ANCAs for WG, caused by a high percentage of PR 3 negative, positive c-ANCA determinations, possibly related to hypergammaglobulinaemia. Anti-PR 3 antibodies have a high ppv for WG. However, neither c-ANCA titre, nor the level of anti-PR 3 antibodies correlated with the activity of the disease.

A comprehensive method to purify three major ANCA antigens: proteinase 3, myeloperoxidase and bactericidal/permeability-increasing protein from human neutrophil granule acid extract

Indirect immunofluorescence (IIF) techniques have shown that anti-neutrophil cytoplasm autoantibodies (ANCA) are useful serological markers for certain small vessel vasculitides and the non-vasculitic inflammatory disorders. ELISA procedures, using purified molecules as solid phase ligands, helped to identify proteinase 3 (PR3) and myeloperoxidase (MPO) as two major ANCA antigens; and recently we characterised bactericidal/permeability-increasing protein (BPI) as another important ANCA antigen. ANCA against these three antigens are associated with different clinical disorders. Therefore purified antigens are needed to determine these different autoantibody specificities in order to help diagnosis and guide treatment. Here we describe a method using Orange-A dye ligand chromatography and cation exchange chromatography for the sequential purification of PR3, MPO and BPI, from the same starting material, an acid extract of normal human neutrophil granules. After separation the three antigens were free of contamination by each other and no traces were found of other known minor ANCA antigens.

Antineutrophil cytoplasmic antibodies (ANCA) in rheumatoid arthritis: a prospective study

To investigate a possible relationship between the presence of antineutrophil cytoplasmic antibodies (ANCA), rheumatoid factor (RF), antinuclear antibodies (ANA), complement, disease activity and disease severity, 111 clinically well-documented RA patients were studied prospectively for ANCA, RF, ANA, C-reactive protein (CRP), total haemolytic complement (CH50) and complement split product C3d. Disease activity and severity were also assessed clinically, as well as anamnestically, using the Hannover Activity of Daily Living Questionnaire, the functional Steinbrocker grades, and numeric and verbal rating scales. At a serum dilution of 1:50, 20% of the 111 sera showed predominantly an atypical perinuclear staining pattern. There was no correlation between ANCA positivity and serological markers, disease activity and disease severity. Regarding previous therapies with disease-modifying antirheumatic drugs, ANCA+ patients took sulphasalazine significantly more often than ANCA- patients.

Anti-neutrophil cytoplasm antibodies (ANCA) in rheumatoid arthritis: relationship to HLA-DR phenotypes, rheumatoid factor, anti-nuclear antibodies and disease severity

To investigate a possible relationship between the presence of anti-neutrophil cytoplasm antibodies (ANCA), rheumatoid factors (RF), anti-nuclear antibodies (ANA), disease severity and HLA-DR phenotypes, 46 consecutive ANCA+ and 48 ANCA-, clinically well-documented RA patients were studied for RF, ANA and HLA-DR phenotypes. The 46 ANCA+ patients showed predominantly an atypical perinuclear staining pattern (89%). ANCA positivity was associated with higher RF titres (P < 0.005) and advanced functional Steinbrocker grades III/IV (P < 0.015). ANCA+ patients were also more often positive for ANA than ANCA- patients (P < 0.008). There was no correlation between ANCA positivity and certain HLA-DR phenotypes although the frequency of DR4+ (67% vs 52%) and, in particular, of DR4+ blanks (phenotypically homozygous) was increased in ANCA+ as compared to ANCA- patients (20% vs 8%). DR4-DR1-RA patients were twice as frequent in the ANCA- than in the ANCA+ group (22.9% vs 8.7%). Correspondingly, the DR4+DR1- phenotype was increased among ANCA+ RA patients. Regarding functional Steinbrocker grades, the DR4+ phenotypes were slightly but not significantly increased in grades III and IV whereas ANCA positivity was significantly associated with severe functional Steinbrocker grades III/IV (66% ANCA+ vs 39% ANCA-, P < 0.015). ANCA positivity identified a population of RA patients with a long-standing and severe clinical course of the disease. There was no correlation between ANCA positivity and certain HLA-DR phenotypes.