[Antineutrophil cytoplasmic antibodies in human pathologies].

The prevalence of antineutrophil cytoplasmic antibodies (ANCAs) was verified in 338 patients with various rheumatic diseases using the internationally standardized indirect immunofluorescence method. The method was improved by using ethidium bromide as a nuclear counterstain. We observed three patterns of fluorescence: the classical diffuse cytoplasmic granular staining (C); the perinuclear one (P) and a yet undescribed atypical cytoplasmic distribution (A). We thus found ANCAs in 14/15 (93%) patients with active Wegener's granulomatosis: 13 were C-ANCAs, 1 was P-ANCA. We also found ANCAs in 6/25 (22%) patients with other systemis vasculitides (essentially those with small vessel vasculitis): they were C-ANCAs (3 cases) or P-ANCAs (3 cases). Finally, ANCAs were detected in 10/185 patients with various autoimmune diseases (5 with rheumatoid arthritis and 5 with systemic lupus erythematosus): they were C-ANCAs (1 case), P-ANCAs (4 cases) or A-ANCAs (5 cases). No ANCAs were found in 100 control patients with miscellaneous diseases. The isotype distribution of ANCAs is essentially limited to IgG classes and the serum titre usually reflects disease activity. The technical improvement facilitates the distinction of ANCAs from other antinuclear and anticytoplasmic autoantibodies found in connective tissue diseases. Our data emphasize the clinical importance of ANCA detection and justify our efforts to develop more specific and quantitative assays.