SYNOVIAL-CELLS ARE POTENT ANTIGEN-PRESENTING CELLS FOR SUPERANTIGEN, STAPHYLOCOCCAL-ENTEROTOXIN-B (SEB)

There is ample evidence suggesting that superantigens may act as a tri ggering factor in the pathogenesis of rheumatoid arthritis (RA). We in vestigated whether superantigen could activate T cells in the presence of synovial cells. T cells were cultured with SEB in the presence of interferon-gamma (IFN-gamma)-treated synovial cells. T cell proliferat ion and activation were assessed by H-3-thymidine incorporation and IL -2 production. The expression of HLA class II antigens and adhesion mo lecules on synovial cells was detected by flow cytometer. In the prese nce of IFN-gamma-treated synovial cells, T cells proliferated vigorous ly and produced IL-2 in response to SEB. A low SEB-induced T cell resp onse was noticed in the presence of untreated synovial cells. Allogene ic as well as autologous IFN-gamma-treated synovial cells markedly enh anced SEB-induced T cell proliferation. IFN-gamma-treated synovial cel ls had increased expression of HLA class II antigens and intercellular adhesion molecule-1 (ICAM-1) adhesion molecules. MoAbs towards these antigens markedly inhibited the SEB-induced T cell response. These res ults indicate that activated synovial cells are potent antigen-present ing cells for SEB to T cells, and that superantigens may play a critic al role in the pathogenesis of RA through activated synovial cells.