Ex Vivo Activated Immune Cells Promote Survival and Stimulate Multilineage Hematopoietic Recovery in Myelosuppressed Mice

Summary: Recovery of multilineage hematopoiesis from severe myelosuppression due to chemotherapy and radiotherapy remains a clinical problem. The authors have developed a simple immunotherapy to treat this disease in a mouse model. Syngeneic spleen cells or xenogeneic human peripheral mononuclear cells were cultured ex vivo with a combination of IL-2 at 500 IU/mL, GM-CSF at 200 U/mL, and calcium ionophore A23187 at 100 ng/mL for 2 days and injected intravenously into mice that had previously received a lethal dose of carboplatin and radiation. The therapy was highly effective: a single injection of activated cells enhanced survival and simulated multilineage recovery of hematopoiesis. Ex vivo activated immune cells produced multiple cytokines, including several hematopoietic growth factors. Adherent cells were found to be more potent than nonadherent cells in promoting survival, and the therapy alone was capable of mobilizing peripheral blood stem cells in normal mice.