Rheumatoid pericarditis: comparison of immunologic characteristics of pericardial fluid, synovial fluid, and serum.

A comparison was made of the immunological characteristics of serum, synovial and pericardial fluids obtained from a 54 year old man with classic rheumatoid arthritis and pericarditis. The synovial and pericardial fluids had low complement levels and immune complexes were detected using both biological and physical methods. The serum had normal complement levels and no immune complexes could be demonstrated. The presence of immune complexes and complement depletion in the synovial and pericardial fluids supports the concept of local production of immune complexes, and is in keeping with a Type III mechanism of immunologic injury.