AUTOANTIBODIES AND TARGET ANTIGENS IN ANTINEUTROPHIL CYTOPLASMIC ANTIBODY (ANCA)-ASSOCIATED VASCULITIDES

In this study of antineutrophil cytoplasmic antibody (ANCA)-associated diseases, we determined the prevalence of other autoantibodies and th e antigen specificities of ANCA. ANA were common, occurring in 7 of 36 (19%) patients with Wegener's granulomatosis, in 16 of 34 (47%) patie nts with microscopic polyarteritis, in 6 of 11 (55%) patients with seg mental necrotising glomerulonephritis and in 8 of 18 (44%) of those wi th ANCA-associated systemic vasculitis without renal involvement. ANA were associated more often with pANCA and microscopic polyarteritis th an with cANCA (P<0.05). Patterns were speckled (n = 23), homogeneous ( n = 10) or nucleolar (n = 4). Anticardiolipin antibodies were also com mon, occurring in 10 of 25 (40%) patients with Wegener's granulomatosi s, in 8 of 14 (57%) patients with microscopic polyarteritis and in 6 o f 18 (33%) of those with a systemic vasculitis. However, anticardiolip in antibodies did not correlate with the presence of ANCA in any of th e disease groups. Anti-GEM antibodies were demonstrated in only 2 of 2 5 (8%) patients with Wegener's granulomatosis, in 1 patient with micro scopic polyarteritis (1/14, 7%) and in 1 with segmental necrotising gl omerulonephritis (1/11, 9%). All four patients with anti-GBM antibodie s had either cANCA or pANCA. In the second part of the study, the targ et antigens of ANCA were determined in Wegener's granulomatosis, micro scopic polyarteritis, systemic vasculitis, inflammatory bowel disease, rheumatoid arthritis and systemic lupus erythematosus (SLE). Of the 1 9 sera with cANCA, 13 (68%) were directed against proteinase 3; other antigens were myeloperoxidase (1/19, 5%), elastase and lactoferrin tog ether (1/19, 5%), lysozyme (1/19, 5%) or unknown (3/19, 16%). Of the 1 2 (58%) sera from patients with Wegener's granulomatosis who had cANCA , 7 bound to proteinase 3. Antimyeloperoxidase antibodies were present in 14 of 45 (31%) sera with pANCA; other antigens were proteinase 3 ( 5/45, 11%), elastase (3/45, 78%), lactoferrin (1/45, 2%), cathepsin G (5/45, 11%) or unknown (17/45, 38%). Antimyeloperoxidase antibodies we re common in microscopic polyarteritis (6/14, 43%) and systemic vascul itis (5/16, 31%). However, the majority of target antigens in systemic vasculitis and rheumatoid arthritis with pANCA were not determined. ' 'Atypical'' ANCA were present in four patients, one with inflammatory bowel disease (1/8, 13%) and three with SLE (3/15, 20%). The specifici ties were cathepsin G, cathepsin G plus lactoferrin, or unknown in two sera. A recent report has suggested that bactericidal/permeability-in creasing protein may be the target in patients with inflammatory bowel disease.