INCREASED PROPORTION OF RESPONDERS TO A MURINE ANTI-CD3 MONOCLONAL-ANTIBODY OF THE IGG1 CLASS IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS(SLE)

A group of Venezuelan patients with SLE showed an increased proportion of responders to Leu-4, an anti-CD3 MoAb of the IgG1 class, compared with ethnically matched non-SLE patients and healthy controls. The rat e of proliferative responses or IL-2 production induced by MoAb Leu-4, and the helper effect of macrophages from Leu-4 responders on T cells from a third-party donor were comparable in patients and controls. No significant differences in the binding of murine IgG1 molecules by ma crophages from SLE patients and controls were observed. The proportion of monocytes/macrophages expressing Fc gamma RI was significantly hig her in SLE patients. However, the expression of FcRII, the type capabl e of supporting Leu-4-mediated responses, and of Fc gamma RIII was com parable in monocytes from SLE patients and controls. Our results sugge st that Venezuelan patients with SLE may have a genetic predisposition for the expression of the phenotypic variant of Fc gamma RII capable of binding murine IgG1 molecules.