Experimental immune inflammation in the synovial membrane. I. The immunological mechanism.

Synovitis was produced in immunized guinea-pigs and rats by injection of antigen into the knee joint. The reaction was mainly mononuclear at 48 hours and, in the guinea-pig, progressed to chronic granuloma formation. Antigens principally used were bovine γ-globulin and tuberculin PPD. Immune deviation, giving a diminished delayed hypersensitivity response, also gave diminished synovial inflammation when compared with undeviated control animals. Immune synovitis to tuberculin PPD was successfully transferred with peritoneal cells taken from immunized animals and given intravenously to normal recipients whose knee joints were injected with antigen. Intravenous transfer of immune serum gave rise to a synovial reaction to bovine γ-globulin, injected into recipients' joints. Transfer of both cells and serum gave rise to particularly severe reactions. Transfer of either cells or serum or cells with serum failed to give reactions extending beyond 3–4 days. This suggests that active immunization is a requisite for the chronic inflammatory reaction of synovitis. Although the 48-hour synovial membrane reaction of rats was similar to that seen in the guinea-pig, chronic inflammatory reactions were not found in that species.