Immune complexes in synovial fluid and serum from patients with disseminated gonococcal infection: evidence for local immune complex formation within the joint.

Twenty one patients with acute arthritis associated with disseminated gonococcal infection (DGI) were studied. Synovial fluid (SF) from 14 and serum from 15 (matched in eight) were assayed for the presence of immune complexes (IC) by the Raji cell immunofluorescent assay (Raji IFA) and the 125I-Clq polyethylene glycol (PEG) binding assay. Higher levels and frequency of IC were detected in the SF by both IC assays and these were associated with a significant increase in complexes containing IgM over serum (p less than 0.02). Complexes containing IgG were found predominantly in serum and were infrequent in SF (p less than 0.003). These data suggest that the arthritis of DGI may result from primary immune complex formation within the synovial cavity after local antibody synthesis within the synovium in response to gonococcal seeding.