Stimulation by thymopoietin oligopeptides of lectin-dependent cell-mediated cytotoxicity in patients with systemic lupus erythematosus.

The effect of thymopoietin penta- (TP-5), tetra-(TP-4), and tripeptides (TP-3) was studied on the depressed lectin-dependent cell-mediated cytotoxicity (LDCC) against adherent HEp-2 target cells by peripheral blood mononuclear cells from patients with active systemic lupus erythematosus (SLE). LDCC activity was evaluated by detachment from the monolayer of 3H-thymidine-prelabelled HEp-2 cells in the presence of concanavalin A (Con A). While 10(-5)M TP-3 moderated the depression, 10(-5) M TP-5 strongly enhanced LDCC activity in SLE patients up to the normal level. On the other hand, LDCC activity by normal donors was not influenced by TP-3 and TP-5. TP-4 had no major effect either in control or in SLE patients. In parallel experiments none of the thymopoietin peptides affected the Con A-induced suppressor activity on the blastogenesis of lymphocytes. A selective immunostimulatory effect of TP-3 and TP-5 on the generation of LDCC effector cells in patients with SLE is suggested.