Immune complexes and the pathogenesis of meningococcal arthritis

Immune complex levels were measured in serum and synovial fluid obtained from 10 patients who developed arthritis 3-8 days after the onset of meningococcal meningitis. Mean serum immune complex levels were lower in these patients than in eight age matched control patients with meningococcal disease who did not develop late complications. This observation suggests that meningococcal arthritis follows local formation of immune complexes in the synovium rather than deposition of circulating immune complexes. Purified meningococcal polysaccharide antigen-induced synovitis when injected into the knee of rabbits previously sensitized by i.v. injection with heat killed meningococci.