INTERLEUKIN-2 RECEPTOR-BETA CHAIN AS A POSSIBLE TARGET FOR LOW-DOSES OF MAFOSFAMIDE

THE 7-day cytotoxic lymphocytes (CTL) induced in mixed lymphocyte cult ure express only the beta chain of the interleukin-a receptor (IL-2R). In the present study this fact has been confirmed in a murine semi-al logeneic system. The ability of low doses of mafosfamide (Mf) to affec t IL-2-induced CTL proliferation has been demonstrated. It was also sh own that IL-2 activated resting suppressor cells. The pretreatment of the suppressor cells with either monoclonal antibodies (mAbs) against the p75 chain of IL-2R, or with Mf abolished the suppressive effect of these cells. No restoration of the proliferative response occurred wh en the anti-IL-2R alpha mAb had been used. Flow cytometry analysis of 7-day CTL was carried out with mAbs against the alpha and beta chains of IL-2R CTL treatment with Mf inhibited anti-IL-2R beta mAb binding. It may be assumed that the antiproliferative effects of Mf which have been demonstrated in this paper, were a result of blocking the IL-2R b eta chain.