SYNOVIAL FIBROBLASTS AS ACCESSORY CELLS FOR STAPHYLOCOCCAL ENTEROTOXIN-MEDIATED T-CELL ACTIVATION

Rheumatoid arthritis (RA) is thought to be the result of T-cell-mediat ed autoimmune phenomena. So far, a critical autoantigen has not been i dentified. Recently, superantigens have been implied in the pathogenes is of RA. In the present study it was tested whether major histocompat ibility complex (MHC) class II-positive synovial fibroblast cells (SFC ) function as superantigen-presenting cells. SFC were stimulated with interferon-gamma (IFN-gamma) to express class II antigens; then they w ere cultivated in the presence of T cells with or without staphylococc al enterotoxins (SE). T-cell activation was measured as proliferation and interleukin-2 (IL-2) production. Depending on the dose and type of SE, activation of T-cell clones and also of peripheral T cells was se en. T-cell activation was inhibited by antibodies to MHC class II anti gens and also by antibodies to intracellular adhesion molecule type-1 (ICAM-1). The data suggest that class II-positive SFC have the capacit y to serve as accessory cells for superantigen-mediated T-cell activat ion. Thus SFC may participate in the propagation of a T-cell dependent immune response.