FUNCTIONAL COMPARISON OF BONE MARROW-DERIVED MACROPHAGES OBTAINED BY CULTIVATION IN SERUM-FREE OR SERUM-SUPPLEMENTED MEDIUM

Bone marrow-derived macrophages obtained by cultivation in a serum-free or in a serum-supplemented medium were compared in terms of the activation of the respiratory burst and the activation of tumor cytotoxicity. Serum-free-cultured macrophages responded to interferon-.gamma. (IFN-.gamma.) and to lipopolysaccharide (LPS) by an enhancement of the respiratory burst. Macrophages obtained in a serum-supplemented medium are characterized by a diminished capacity to release .**GRAPHIC**. These cells did not respond to IFN-.gamma. unless the stimulation was performed in a serum-containing medium. In terms of activation of tumor cell cytotoxicity, serum-supplemented macrophage cultures seem to be primed by unknown serum constituents because they only need one signal (IFN-.gamma. or LPS) to become fully cytotoxic. Serum-free cultivated macrophages can be rendered cytotoxic only after exposure to combinations of IFN-.gamma. and LPS.