Leukoregulin inhibits the growth of human glioblastoma in vitro

Growth of cultured human glioblastoma cells was profoundly inhibited by concentrated lymphokines prepared from mitogen-activated blood mononuclear cells of normal donors. Cloning efficiency of glioma cells and their absolute number were decreased as well. Partially purified leukoregulin, free of lymphotoxin, tumor necrosis factor and gamma-interferon, similarly suppressed DNA synthesis and clonogenicity. The decrease in absolute numbers of tumor target cells indicated that leukoregulin was directly cytolytic as well as cytostatic for human glioblastoma cells. Our data indicate that leukoregulin is at least one of the factors produced by activated lymphocytes which inhibits the proliferation of human glioblastoma in vitro.