| Abstract: | Patients with systemic lupus erythematosus (SLE) have decreased precursors of cytotoxic/suppressor T lymphocytes in their peripheral blood, as determined by monoclonal antibodies. To determine whether decrease of the cytotoxic or the suppressor parts (or both) of this subpopulation of T lymphocytes is being reflected by this peripheral mononuclear cell (MNC) abnormality, a series of experiments was conducted in which both the suppressive function (concanavalin A induced and spontaneous) and the generation of cytotoxic responses against alloantigens were tested. Cytotoxic responses were consistently diminished while suppressor capacity of MNC from patients with SLE (measured on several assays of normal T- and B-lymphocyte functions) was comparable to that of MNC from normal individuals. The defect in cytotoxic responses to alloantigens by MNC from SLE patients persisted following secondary stimulation in mixed-leukocyte cultures; the cytotoxic responses were not amplified and remained well below the responses of normal MNC. These experiments indicate that the decreased peripheral population of cytotoxic/suppressor lymphocytes in SLE patients represents low or absent precursors of cytotoxic cells rather than of precursors of suppressor cells. |
