Cytotoxic Activity of Lymphocytes and Sera from New Zealand Mice against Allogeneic Fibroblasts

Using NZB/NZW F1 hybrid (B/W) mice, in model experiments for human systemic lupus erythematosus, the cytotoxic activity of thymocytes and splenic lymphocytes was studied against allogeneic target cells. Lymphocytes from female B/W mice were proved to have cytotoxic activity against target cells by the 51Cr release technique. The activity of splenic lymphocytes was a little higher than that of thymocytes. Antinuclear antibody (ANA) positive sera from B/W mice also accelerated the release of 51Cr from the target cells with the cooperation of complement. Pretreatment of B/W lymphocytes with DNA or addition of DNA to the culture medium did not affect their cytotoxicities. Natural thymocyto-toxic autoantibody was not found in B/W sera. The percentage of θ negative thymocytes in B/W mice (11-21%) was considerably higher than that in control mice (0-2%). From these results, it is supposed that the cell-mediated immunity against self-antigens besides autoantibodies constitutes a very important factor in the development of autoimmune diseases.