The role of antibodies to IL-2 receptor and Asialo GM1 on graft-versus-leukemia effects induced by bone marrow allografts in murine B cell leukemia.

The role of various cell subpopulations involved in the graft-versus-leukemia (GVL) effect induced by allogeneic bone marrow transplantation (BMT) was investigated in (BALB/c x C57BL/6)F1 (F1) recipients, inoculated with murine B cell leukemia (BCL1), by using monoclonal murine anti-IL-2 receptor antibodies or rabbit anti-Asialo GM1 antibodies directed predominantly against murine NK cells. F1 mice with BCL1 were irradiated and reconstituted with parental (C57BL/6) bone marrow cells (BMC) or a mixture of BMC and spleen cells and treated in vivo for 10 days with anti-IL-2 receptor antibody or anti-Asialo-GM1 antibody. Both treatments lessened the GVL effects induced by the allograft and resulted in development of leukemia relapse, as documented in vivo by adoptive transfer of 10(5) spleen cells obtained from treated mice into secondary syngeneic adoptive recipients. Our data indicate that IL-2 receptor-positive T cells and possibly IL-2-activated allogeneic NK cells play a key role in inducing GVL following allogeneic BMT.