Interaction of antibodies with Entamoeba histolytica trophozoites from experimental amebic liver abscess: an immunocytochemical study

Using immunocytochemical techniques, we studied the interaction of antibodi es with Entamoeba histolytica trophozoites present during the development o f amebic liver abscess. Hamsters were intrahepatically inoculated with HM1- IMSS axenic amebas and sacrificed at different days post-inoculation. IgG o f rabbit anti-E. histolytica and IgG of rabbit anti-IgG of hamster were use d, both labeled with peroxidase. With the rabbit anti-E. histolytica, all t rophozoites present in hepatic lesions from 1-7 days post-inoculation were highly labeled. The IgG of rabbit anti-IgG of hamster intensively stained o nly those trophozoites present in lesions from 1-2 days post-inoculation. F rom day 3! the intensity and number of labeled trophozoites decreased progr essively. The results suggest that the interaction between the amebas and t he IgG of hamster is non-specific during the first 2 days. The absence of l abeling in the chronic stages could be due to changes in the membrane antig ens of the parasite or to alterations in the bloodstream around necrosis. A lso, the anti-E. histolytica antibodies produced in the serum during the de velopment of the hepatic disease are apparently incapable of reaching and i nteracting with the trophozoites present on the liver abscess. This can exp lain in part why antibodies do not have an important role in the defense of the host.