In vivo and in vitro macrophage activation by systemic adjuvants

Six systemic adjuvants of immunity were tested for their ability to induce macrophage activation. Four of them: living BCG, hydrosoluble extracts from BCG (HIU II) and from M.smegmatis (IPM), and lipopolysaccharide from E.coli (LPS), when administered to normal mice render macrophages non-specifically cytotoxic for tumor cells in vitro. The intensity of this phenomenon varied according to the route and time of adjuvant administration. In contrast, lentinan extracted from Lentinus edodes, and levamisole which is a synthetic chemical compound, depressed macrophage cytotoxic potential. BCG, IPM and LPS were shown to have a direct action on macrophages. After in vitro exposure to these agents, the cytotoxic potential of normal macrophages was greatly increased. Levamisole was unable to stimulate this macrophage function directly in vitro. On the other hand, such a macrophage activation has been induced in vitro when normal macrophages were cultivated in the presence of MIF coming from the supernatant of human lymphoblastoid cell lines.