Interleukin-2 in bone marrow transplantation: preclinical studies.

Interleukin-2 (IL-2) promotes the generation and proliferation of killer cells in the peripheral blood and bone marrow (BM) both in vitro and in vivo. When employed in a syngeneic bone marrow transplantation (BMT) setting and followed by IL-2 therapy, murine BM cells activated with IL-2 in vitro (ABM) demonstrate potent graft-versus-leukemia (GVL) and anticytomegalovirus effects. ABM cells retain the capacity to reconstitute the hemopoietic system both in normal and leukemic mice. This therapy does not cause graft-versus-host disease (GVHD). Human ABM cells carry out purging of leukemia without loss of progenitor cell activity in vitro. The purging ability of ABM can be augmented by interleukin-1, interferon, and tumor necrosis factor. IL-2 therapy stimulates the veto suppressor cell activity of T cell-depleted BM, and has reduced GVHD and permitted engraftment of mismatched allogeneic BM in murine models. Future studies should determine the optimum treatment schedules with IL-2 for improving the GVL effect in autologous BMT, and for abolishing GVHD in allogeneic BMT settings.