ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN SYSTEMIC LUPUS ERYTHEMATOSUS

Antineutrophil cytoplasmic antibodies (ANCA) with specificityfor proteinase-3 (PR3) are associated with Wegener's granulomatosis,and ANCA directed to myeloperoxidase (MPO) with other idiopathicvasculitides. Inflammation of small-sized blood vessels is ahallmark of systemic lupus erythematosus (SLE). We evaluatedthe prevalence of ANCA in SLE, their antigenic specificities,and their possible relation to clinical disease patterns andactivity. Plasma samples from 84 patients with SLE were testedfor ANCA during remission. Plasma samples from the 25 patientswho relapsed during a follow-up of 32 months were serially analysedfor ANCA in a 6 month period preceding and including the relapse.The presence of ANCA was assessed by indirect immunofluorescence(IIF) and ELISA for antibodies to PR3, MPO, lactoferrin (LF),elastase (HLE) and cathepsin-G (CG). We related the presenceof ANCA to disease patterns, activity and duration. ANCA byIIF were difficult to interpret due to the presence of antinuclearantibodies (ANA). By ELISA, we found no anti-PR3 or anti-HLE.Anti-MPO (n = 7), anti-LF (n = 13) and anti-CG (n = 10) weredetected, generally in low titres. The presence of ANCA of definedspecificity was not associated with specific clinical subsets.The prevalence of ANCA was higher in patients who developedrelapses than in those who did not (P < 0.01). However, levelsof ANCA did not fluctuate in the period preceding the relapse.ANCA of various specificities occur in SLE. Their presence isnot associated with specific clinical disease entities. Thehigher frequency of ANCA in relapsing patients compared to thosewho do not relapse may suggest that ANCA are involved in diseaseexpression. Their diagnostic significance is limited. KEY WORDS: ANCA, SLE, Disease activity, ELISA