In vitro studies on lymphocytotoxicity to synovial cells and Chang cells in rheumatoid arthritis patients and healthy controls.

Lymphocytotoxicity to autologous or allogeneic synovial cells and Chang cells was studied in 27 patients with rheumatoid arthritis (RA), in 5 patients with osteoarthrosis of the hip or knee and in 17 healthy controls. Ficoll gradient-separated lymphocytes from the peripheral blood, T cells and non-T cells were used as effector cells. T lymphocytes were isolated as E-rosette forming cells 10 percent of which carried Fc- receptors. The differential counts for T and B cells in the peripheral blood of the RA and osteoarthrosis patients were approximately the same as in the blood of the healthy controls. The counts of Fc-receptor-bearing cells in the RA patients were, however, significantly higher. Cytotoxic reactivity of lymphocytes from RA patients, osteoarthrosis patients or healthy controls to synovial cells of autologous or allogeneic origin could not be demonstrated in our study, in which 125I-iododeoxyuridine labelled target cells were used in the microcytotoxicity test of Cohen et al. However, lymphocytes of the peripheral blood showed an increased cytotoxicity to Chang cells, an effect for which Fc-receptor bearing cells were responsible. Serum did not affect the cytotoxicity of lymphocytes. The results are interpreted as demonstrating an enhanced natural killer (NK) cell activity in RA patients; they do not indicate a specific cell mediated immune reaction to synovial cells.