Antineutrophil cytoplasmic antibodies in reactive arthritis.

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.