Salmonella specific antibodies in serum and synovial fluid in patients with reactive arthritis.

The occurrence of Salmonella specific antibodies was analysed in paired serum and synovial fluid samples from 12 patients with Salmonella triggered reactive arthritis. The antibody concentration of IgA2 subclass in synovial fluid exceeded that of serum in 8 of the 12 pairs studied, compared to 0-3 in the other immunoglobulin classes and subclasses. This finding indicates intra-articular production of IgA2 class antibodies against the triggering microbe.