Immunosuppression and splenomegaly in Entamoeba histolytica infection in mice.

Intestinal amoebiasis caused by Entamoeba histolytica trophozoites in mice is accompanied by a depression in the ability of this host to develop an immune response to sheep red blood cells. The number of splenic plaque-forming cells was reduced in mice inoculated intracecally with 2.5 x 10(5) trophozoites at 15, 25, 40, 65 and 75 days after infection when compared with non-infected mice. It was found that there was no significant difference between the spleen weight of the infected and non-infected control animals at 5 and 10 days following infection. However, a significant increase in spleen weight was observed by 15 days of infection and the spleens remained enlarged until termination of the experiment at 75 days. Thus, there was an inverse correlation between the PFC response and the spleen weight of infected animals.