Autologous mixed lymphocyte reactions in rheumatoid arthritis. Characterization of stimulator cells and the recognition unit for autoantigens on the responder cells.

Reduced lymphocyte responses were detected in the peripheral blood (PB) of patients with rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA) in the autologous mixed lymphocyte reaction (AMLR) using irradiated non-T cells as stimulator cells and T cells as responder cells. The AMLR responses of synovial tissue (ST) and of synovial fluid (SF) lymphocytes were normal. Dendritic cells both from the peripheral blood (PB), ST and SF were very potent stimulators in the AMLR and in vivo activated, HLA-DR positive T cells both from ST and SF were able to stimulate autologous PB T-cells in both RA and JRA patients. A rabbit antiserum produced against a fragment comprising the variable heavy (VH) chain region of an IgG3 human myeloma protein (Kup) reacted with peripheral blood T cells and inhibited the AMLR responses. Thus, VH antigens are integral parts of the T cell receptor for autologous HLA-DR (Ia) antigens.