ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN REACTIVE ARTHRITIS

Objective, To study the occurrence of antineutrophil cytoplasmic antib odies (ANCA) in reactive arthritis (ReA). Methods. Sera from 22 patien ts with ReA were analyzed by ELISA for the presence of autoantibodies (IgG and IgA) against a proteinase-3 containing azurophilic granule ex tract (''alpha-antigen'') from human polymorphonuclear leukocytes, mye loperoxidase (MPO), and lactoferrin (Lf), respectively. Rheumatoid fac tor (RF), antinuclear antibodies (ANA), and HLA-B27 were also tested. Erythrocyte sedimentation rate and serum levels of C-reactive protein were used to assess disease activity. The patients were divided into a cute or chronic (>1 year) disease. Results, 12/22 patients (55%) had I gG ANCA (7 had MPO ANCA, 8 had Lf ANCA, and 1 had alpha-ANCA). Eight p atients (36%) had IgA ANCA. One serum was positive only for IEA ANCA. 18/21 patients (85%) were HLA-B27 positive, and none had RF or ANA. Th e triggering infection was Chlamydia trachomatis in 6 cases, Campyloba cter jejuni in 6, Yersinia enterocolitica in 4. In 6 patients the caus ative microorganism could not be determined. ANCA was more prevalent i n chronic disease (6/7, 82%) compared to acute (7/15, 47%). No obvious correlation was seen between ANCA and disease activity, Conclusion, A NCA, predominantly those reacting with Lf and/or MPO preparations, are common in ReA.