Macrophage requirement for host defence against experimental hepatic amoebiasis in the hamster

The role of macrophages in hepatic amoebiasis in hamsters has been investigated by means of their treatment with bacille Calmette-Guérin (BCG) for activation, and with silica for elimination of these cells. Silica-treated animals inoculated intrahepatically with 1 x 10(5) trophozoites of Entamoeba histolytica developed amoebic abscesses in the liver and more metastases to other organs than control animals, and this effect was silica-dose-dependent. In contrast, BCG-treated animals developed significantly smaller abscesses in the liver and fewer metastatic foci. These data suggest that macrophages are involved in host defence against the establishment of amoebic liver abscess and metastatic dissemination of amoebae.