Infectious agents and other nongenetic immunologic factors in spondyloarthropathies.

Because one of the spondyloarthropathies, reactive arthritis, is induced by infections, research into the role of arthritis-causing bacteria has been strongly emphasized. The most remarkable finding in recent years is the detection of some of the bacterial components in the articular compartment, in some cases even several years after the development of arthritis. This location would account for the fact that T lymphocytes in the synovial compartment demonstrate a high in vitro response to preparations of the arthritis-causing bacteria. The persistence of these bacterial components would explain the frequently reported prolonged antibacterial antibody response in arthritis patients. Although the factors leading to the location and persistence of the bacteria are not clear, the finding provides a rationale for treating these patients with long-term antibiotics. A major question being investigated is how the presence of bacterial components in the articular compartment is related to the predominance of HLA-B27 in many of the patients.