INDUCTION OF IMMUNOLOGICAL-TOLERANCE TO ISLET ALLOGRAFTS

T-cell dependent activation of resting B cells involves the interactio n of gp39 on T cells with its receptor, CD40, on B cells. We administe red either a combination of T-cell-depleted splenic lymphocytes and an ti-gp39 monoclonal antibody or antibody alone to establish islet allog rafts in mice without continuous immunosuppression. Fully allogeneic H -2(q) FVB islets were permanently accepted by chemically diabetic H-2( b) C57BL/6 mice provided that the recipients were pretreated with both T-cell-depleted donor spleen cells and anti-gp39 antibody. Antibody a lone was less effective in prolonging allograft survival, but we did o bserve that anti-gp39 mAb alone can exert an independent, primary effe ct on islet allograft survival that was dose dependent. Targeting gp39 , in combination with lymphocyte transfusion, might prove suitable for tolerance induction and allotransplantation without immunosuppression .