Responsiveness of T lymphocytes from systemic lupus erythematosus to signals provided through CD26 antigen.

To investigate whether the T cell defective capacity to proliferate observed in systemic lupus erythematosus (SLE) T cells is a possible consequence of an intrinsic T cell disorder, the integrity of the accessory activation pathway mediated through CD26 antigen in SLE T cells was studied. Hyporesponsiveness of peripheral blood mononuclear cells (PBMC) from SLE to PHA and CD26 Mab was observed and no differences were found when the responsiveness of highly purified T cells to IL-2, IL-2 plus CD26 Mab, phorbol 12-myristate 13-acetate (PMA), or when PMA plus CD26 Mab was analyzed. Findings suggest that signals induced by triggering CD26 are not intrinsically altered in SLE T cells. However, some alteration of the regulatory involvement of monocytes or B cell over T cell function may be involved.