In Vitro Study of Deoxymethylspergualin on Functions of Lymphocytes and Bone Marrow Cells from Healthy Volunteers

15-Deoxy-11-O-methylspergualin (MeDSG) is an analogue of 15-deoxyspergualin, which has potent immunosuppressive activity. The present study was designed to evaluate the in vitro effects of MeDSG on the functions of peripheral blood mononuclear cells (PBMC) and bone marrow cells derived from healthy volunteers. MeDSG failed to suppress the proliferation of PBMC stimulated with mitogens. In the allogeneic mixed lymphocyte reaction, MeDSG strongly suppressed both the proliferation of lymphocytes and the generation of alloreactive cytotoxic T lymphocytes, but did not affect the cytolytic activity of the established cytotoxic T lymphocytes. MeDSG had no effect on the cytolytic activity of natural killer cells. Concerning positive hematopoietic regulators, MeDSG had a slight enhancing effect on the release of granulocyte-macrophage colony-stimulating factor and a slight inhibitory effect on the release of interleukin-6 and granulocyte colony-stimulating factor from PBMC stimulated with mitogens. Significantly, MeDSG completely suppressed the colony formation of bone marrow cells in the presence of granulocyte colony-stimulating factor.