Effect of various digestive enzymes on the interaction of Toxoplasma gondii with macrophages.

The participation of resident, elicited, and activated macrophage surface components during internalization of tachyzoites of Toxoplasma gondii was analyzed using neuraminidase, phospholipase C, trypsin, protease, and hyaluronidase. Treatment of these macrophages with neuraminidase from Vibrio cholerae, phospholipase C from Bacillus cereus and Clostridium perfringens, protease, and hyaluronidase prior to their interaction with parasites increased the penetration of host cells by T. gondii. Incubation of macrophages with trypsin significantly inhibited the uptake of parasites. Our findings confirm previous observations that treatment of the macrophages with cytochalasin D under conditions that completely block the typical phagocytic process partially inhibits infection of the cells by T. gondii. The results of simultaneous treatment of the macrophages with enzymes and cytochalasin D suggested that the observed enhancement of cell infection by treatment with neuraminidase and hyaluronidase was attributable to a classic phagocytic process, whereas that obtained using phospholipase resulted from active penetration.