The role of the macrophage in immunity to Trypanosoma musculi.

Trypanosoma musculi was killed by adherent peritoneal exudate cells which had the typical appearance of macrophages. Observations by light and electron microscopy showed that the trypanosomes were phagocytozed and killed intracellularly within phagocytic vacuoles of mouse macrophages. Adherence, phagocytosis and killing of T. musculi required the presence of serum from mice immune to this parasite. Phagocytosis and killing of T. musculi was highly dependent on heat-labile factors in immune mouse serum.