The frequency of antineutrophil cytoplasmic antibodies in systemic lupus erythematosus and their association with disease activity and clinical-laboratory parameters

ABSTRACT THE FREQUENCY OF ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN SYSTEMIC LUPUS ERYTHEMATOSUS AND THEIR ASSOCIATION WITH DISEASE ACTIVITY AND CLINICAL-LABORATORY PARAMETERS Antineutrophil cytoplasmic antibodies (ANCA) are a class of antibodies with varied specificity against lysosomal constituents of neutrophils and occur in a wide variety of ' inflammatory disorders. Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disease which is characterized with involvement of varied organ systems and with a wide. range of autoantibodies. In this respect, the purpose of this study was to determine the. presence of ANCA and their target antigens in patients with SLE, and to evaluate their association with specific clinical manifestations and disease activity. Forty patients with SLE, 21 patients with rheumatoid arthritis (RA) and 19 healthy controls (HC) were included in this study. Disease activity Jor SLE was measured using SLE disease activity index (SLEDAI). ANCA detection was performed by indirect immunofluorescence (DF), and by ELISA for proteinase 3 (PR3) and myeloperoxydase (MPO) subspecificities. While 14 (35%) patients with SLE and 1 (4.8%) patient with RA had positive ITF stains, none (0%) of the HC showed positive reaction for ÜF. Five (12.5%) of 41 SLE patients were positive for anti-PR3 and 3 (75%) for anti-MPO. Anti-PR3 was found positive in 1 (4.8%) and anti-MPO in 2 (9.5%) of patients with RA but no reactivity was observed to either antigen in the sera of HC. There were associations betweeen HF-ANCA and anti-PR3 ANCA (p=0.003) and between IIF-ANCA and anti-MPO ANCA (p=0.037) in SLE patients but not in RA patients (p>0.05). The presence of ANCA was not associated with the specific clinical subsets and with the activity of SLE. Although our results demonstrate that ANCA are detectable in the sera of patients with SLE, lack of their association with disease activity and with specific clinical manifestations may suggest that further studies are needed to determine their possible roles in SLE. Key Words: Antineutrophil cytoplasmic antibodies, Systemic lupus erythematosus