Immunobiological function of normal rabbit synovial cells.

The ability of enzyme-dissociated primary cultures of synovial cells (Sy) to present antigen was investigated. Adult rabbits were immunized in foot pads with bovine serum albumin (BSA) in complete Freund's adjuvant (CFA) or with CFA alone. Four to six weeks later draining popliteal lymph node cells (LNC) and synovial cells were obtained. Synovial cells were cultured overnight with or without antigen. About 20% of these synovial cells had Fc receptors and 15% C3 receptors. As a positive control splenic adherent cells (SAC) were similarly treated. Next day, autologous lymph node cells were added to the extensively washed and irradiated synovial cells or splenic adherent cells. Lymphocyte proliferation was measured by [3H]thymidine uptake. Synovial cells as well as splenic adherent cells induced mixed lymphocyte reaction (MLR) and autologous mixed lymphocyte reaction (AMLR) and effectively presented antigen for specific immune response to the priming antigen. Thus, the synovium contains macrophage-like cells that can effectively interact with lymphocytes and participate in the immune phenomena in the joints of patients with rheumatoid arthritis.