The Serum Factor Stimulating Colony Formation In Vitro by Murine Plasmacytoma Cells: Response to Antigens and Mineral Oil

Abstract

Colony formation in agar-medium by three transplanted mouse plasmacytomas (MOPC-460; MOPC-315; HPC-127) was stimulated by addition of serum from mice injected with endotoxin or a variety of bacterial antigens. This effect was potentiated by the addition of mercaptoethanol. The active serum factor was heat-labile but resisted ether treatment and was non-dialysable. Serum plasmacytoma-stimulating activity was localized electrophoretically as a single peak of β mobility and was separable from the colony-stimulating factor stimulating granulocytic and macrophage colony growth. Injection of mineral oil to BALB/c mice increased the capacity of serum or peritoneal cells to stimulate plasmacytoma colony formation in vitro.