HLA-DR4DW4-RESTRICTED T-CELL RECOGNITION OF SELF ANTIGEN(S) IN THE RHEUMATOID SYNOVIAL COMPARTMENT

The pathogenesis of joint destruction in rheumatoid arthritis remains ill defined, although it is thought to be the result of tissue damage mediated by T cells. This prompted us to isolate and characterize in vivo activated T cells from rheumatoid arthritis synovial fluid in an attempt to determine their specificity. Heterogeneous synovial fluid cells, containing both adherent and non-adherent cell types, were recovered from joint aspirates and cultured in the presence of IL-2. After 2 weeks, the non-adherent cells were phenotyped as CD3-positive and TCR alpha-beta-positive T cells. Polyclonal T cell lines were derived from four rheumatoid arthritis patients; of these, two proliferated, in a dose-dependent manner to only autologous synovial fluid in the presence of autologous or DR4Dw4 histocompatible antigen presenting cells. T cell proliferation to the synovial fluid could be inhibited by monomorphic anti-HLA-DR monoclonal antibody, but not by anti-DQ or anti-class I antibodies. T cell clones were established by limiting dilution of a synovial T cell line in the presence of autologous synovial fluid and DR4Dw4 histocompatible accessory cells. Examination of the antigen specificity of these T cell clones demonstrated that they were reactive with a component of synovial fluid. The results of these experiments suggest the presence of an MHC class II-restricted antigen in the rheumatoid arthritis synovial compartment that induces proliferation of in vivo activated T cells.