Differential sensitivity of functional subsets of T cells to the cytotoxicity of natural T-lymphocytotoxic autoantibody of systemic lupus erythematosus.

A naturally occurring T-lymphocytotoxic autoantibody (Hu-NTA) in serum from a patient with systemic lupus erythematosus (SLE) showed a differential cytotoxic effect on functionally different T cell subsets as did natural thymocytotoxic autoantibody (NTA) of NZB mice. When the normal peripheral blood lymphocytes were treated, in the presence of complement, with Hu-NTA at a dilution that eliminated 25 to 30% of Hu-NTA-sensitive T cells, there was a marked reduction or a total depletion in the ability of resultant cells to show Con A-activated suppression on the proliferative response of responder cells in mixed lymphocyte reaction. The treatment of PBL in the same manner also resulted in a marked reduction in its responsiveness to Con A and PHA. However, the responder cells to allogeneic stimulator cells in MLR were found to be much more resistant to the cytotoxicity of Hu-NTA than other functional T cell subsets tested. These results suggest that Hu-NTA is responsible for the selective loss of certain functional T cell subsets including suppressor T cells in patients with SLE.