Indirect evidence of intra-articular immunoglobulin G synthesis in patients with Chlamydia trachomatis reactive arthritis.

Abstract

To investigate whether B-cell stimulation occurs in joints of Chlamydia trachomatis reactive arthritis patients by comparing the immunoglobulin G (IgG) anti-C. trachomatis antibody responses in serum and synovial fluid (SF). The number and spectrum of C. trachomatis antigens recognized by paired serum and SF samples from 16 patients with C. trachomatis reactive arthritis and 20 patients with other inflammatory arthropathies independent of this bacteria, were studied by immunoblotting. The responses to five different Chlamydia antigens were also determined in enzyme-linked immunosorbent assays. In C. trachomatis reactive arthritis patients, a higher number of C. trachomatis antigens was recognized by SF (17.6+/-5.1) than by serum (11.1+/-6.3) IgG and a higher intensity of SF IgG binding to the outer membrane protein 2 (OMP2) was observed. These results suggest an intra-articular IgG production and a possible role of some Chlamydia antigens like OMP2 in the pathogenesis of C. trachomatis reactive arthritis.