Objective: To study the occurrence of antineutrophil cytoplasmic antibodies (ANCA) in reactive arthritis (ReA).
Methods: Sera from 22 patients with ReA were analyzed by ELISA for the presence of autoantibodies (IgG and IgA) against a proteinase-3 containing azurophilic granule extract ("alpha-antigen") from human polymorphonuclear leukocytes, myeloperoxidase (MPO), and lactoferrin (Lf), respectively. Rheumatoid factor (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 acute or chronic (> 1 year) disease.
Results: 12/22 patients (55%) had IgG ANCA (7 had MPO ANCA, 8 had Lf ANCA, and 4 had alpha-ANCA). Eight patients (36%) had IgA ANCA. One serum was positive only for IgA ANCA. 18/21 patients (86%) were HLA-B27 positive, and none had RF or ANA. The triggering infection was Chlamydia trachomatis in 6 cases. Campylobacter jejuni in 6, Yersinia enterocolitica in 4. In 6 patients the causative microorganism could not be determined. ANCA was more prevalent in chronic disease (6/7, 82%) compared to acute (7/15, 47%). No obvious correlation was seen between ANCA and disease activity.
Conclusion: ANCA, predominantly those reacting with Lf and/or MPO preparations, are common in ReA.