Stimulation of macrophages by cord factor and by heat-killed and living BCG.

Trehalose-6,6'-dimycolate (cord factor; CF) injected into the peritoneal cavity of mice induced stimulation of the peritoneal macrophages, evidenced both by increased activity of the lysosomal enzyme, acid phosphatase, and by increased phagocytosis of Listeria monocytogenes. The increase in enzyme activity and phagocytosis was similar to that induced by killed or living BCG. When administered intravenously, CF or BCG did not induce stimulation of peritoneal macrophages. CF when added to tissue cultures of normal peritoneal cells did not induce increased acid phosphatase activity or increased phagocytosis of L. monocytogenes.