ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN SYSTEMIC LUPUS-ERYTHEMATOSUS- PREVALENCE, SPECIFICITIES, AND CLINICAL-SIGNIFICANCE

Objective. To examine the prevalence, subspecificities, and clinical a ssociations of antineutrophil cytoplasmic antibodies (ANCA) in patient s with systemic lupus erythematosus (SLE), Methods. One hundred fifty- seven sera from 120 patients with SLE were examined for classic (c) an d perinuclear (p) pattern ANCA by indirect immunofluorescence, Antibod y subspecificities were determined by enzyme-linked immunosorbent assa y (ELISA), Serologic results were correlated with clinical manifestati ons as categorized by the BILAG (British Isles Lupus Assessment Group) index, Results. ANCA were found in 40 of the 157 sera (25%), Only a p ANCA, not a cANCA, pattern of fluorescence was seen, By ELISA testing, 16 sera reacted to lactoferrin, 8 to elastase, and 4 to lysozyme, The re was no reactivity to proteinase 3 (PR3) or myeloperoxidase (MPO), N o correlation of pANCA, or any of the ANCA subspecificities, with orga n system involvement, as categorized by the BILAG index, was found, No tably, there was no correlation of ANCA results with lupus vasculitis. Conclusion. The absence of cANCA, anti-PR3, and anti-MPO shows that w ith appropriate assay conditions, ANCA testing assists in the differen tiation between SLE and the ANCA-associated vasculitides. The lack of a correlation between pANCA or any ANCA subspecificity and clinical ma nifestations suggests that ANCA do not identify particular clinical su bsets among SLE patients, including those with lupus vasculitis.