Interactions of macrophages from in vivo stimulated guineapigs & the trophozoites of Entamoeba histolytica.

ABSTRACT

The interactions between peritoneal macrophages obtained from guineapigs immunized with a Sephadex chromatographed fraction (FI) of crude amoebic extract proteins and trophozoites of axenic E. histolytica (NIH200) were studied in vitro in the presence or absence of anti FI antiamoebic antibodies. Unstimulated macrophages killed trophozoites to some extent. Incorporation of anti FI antiamoebic antibodies or IgG of FI antibodies in the amoebae macrophages mixture significantly enhanced the cytotoxic potentials of both unstimulated and in vivo stimulated peritoneal macrophages. Transmission electron microscopy revealed a close contact between macrophages and E. histolytica trophozoites. A large number of lysosomal vacuoles were seen accumulating near the contact areas. The contact between peritoneal macrophages and amoebic trophozoites in the presence of anti FI antibodies led to extensive degeneration of amoebic trophozoites. The antiamoebic antibodies induced cytotoxicity by macrophages in an opsonic manner. The data suggest that antiamoebic IgG binding to the trophozoites by its Fab portion and to the macrophages by its Fc portion initiated the cytotoxic mechanism(s) of macrophages.