Studies of immune functions of patients with systemic lupus erythematosus. T-cell subsets and antibodies to T-cell subsets.

Antibodies to T cells present in the plasma of patients with active systemic lupus erythematosus (SLE) plus complement are able to eliminate concanavalin A-induced suppressor function for the proliferative responses of T cells to allogeneic lymphocytes (MLR) and of B cells to pokeweed mitogen (PWM). Such antibodies were found to be effective in eliminating suppressor function only when T cells were treated before activation; there was no effect when treatment was performed after activation. These studies indicate that the antibodies preferentially interact with a T cell necessary for the generation of suppressor cells, rather than with mature, activated suppressor cells. Studies of individual SLE patients indicate that the same defects observed in SLE T cells were induced in normal T cells by plasma from that patient. Such observations suggest that many T-cell defects associated with active SLE may not be intrinsic T-cell abnormalities, but, rather, secondary effects of anti-T-cell antibodies. Studies of the T-cell subpopulations responsible for suppression of the MLR and PWM responses indicate that only T gamma cells (T cells bearing receptors for the Fc portion of immunoglobulin [Ig]G) acted as precursors of suppressor cells for the MLR, whereas both T gamma and T non-gamma cells (T cells not bearing receptors for the Fc portion of IgG) could be activated to suppress the PWM response. Consistent with this observation, SLE anti-T-cell antibodies that preferentially killed T gamma cells preferentially eliminated suppressor cells for the MLR.