Interleukin-7 induced facilitation of immunological reconstitution of sublethally irradiated mice following treatment with alloreactive spleen cells in a murine model of B-cell leukemia/lymphoma (BCL1)

Interleukin-7 (IL-7) plays a key role in maturation and function of both T and B cells. We investigate the potential use of recombinant human IL-7 for facilitation of graft-versus-leukemia (GVL) effects mediated by T cells following transplantation in a murine model. Administration of IL-7 in vivo to allogeneic-transplanted mice improved disease-free survival: 67% of mice treated with IL-7 remained alive and disease free for more than 60 days, in comparison to 17% of the controls (P<0.05). Similar results were obtained when C57BL/6 spleen cells sensitized against irradiated B-cell leukemia (BCL1) cells in the presence of IL-7 were transplanted to F1 mice, followed by IL-7 treatment in vivo. Of the BALB/c mice that received spleen cells from F1 mice treated with IL-7 following transplantation of C57BL/6 spleen cells sensitized with irradiated BCL1 in the presence of IL-7, only 29% developed leukemia, as compared to 79% in the control group (P<0.05). Mice treated with IL-7 showed increased splenic and thymic cellularity and improved T cell-dependent proliferative responses compared to the controls (P<0.05). IL-7 may provide a novel tool to enhance immune reconstitution following transplantation of mismatched stem cells and for enhancement of GVL effects mediated by alloreactive lymphocytes.