Synovial lymphocyte response to chlamydial stimulation associated with intrasynovial chlamydial antigen in a patient with "rheumatoid arthritis".

A 48-year-old man with "rheumatoid arthritis" of 3 years duration was found to have synovial fluid lymphocytes that were maximally stimulated in vitro by chlamydial antigen, on 5 of 6 tests over 18 months. Immunocytochemical staining of a synovectomy specimen, using the peroxidase-antiperoxidase technique, subsequently revealed chlamydial antigen in the synovium. The possibility that Chlamydia in the synovium may produce features of rheumatoid arthritis is discussed.