Parasitol Res. 1995;81(6):475-80.
Intestinal amebiasis: cyclic suppression of the immune response.
Departamento de Inmunología, Universidad Nacional Autónoma de México, México, D. F.
The cellular immune response was evaluated in a C3H/HeJ mouse model of intestinal amebiasis at 5-60 days postinoculation with Entamoeba histolytica. At various intervals, spleen lymphocytes were obtained from infected and noninfected control mice and cultured with concanavalin A (Con A), pokeweed mitogen (PWM), or ameba antigen. E. histolytica infection induced a cyclic depression of DNA synthesis when spleen lymphocytes were stimulated with a T-cell mitogen (Con A), a T- and B-cell (PWM) mitogen, or an ameba antigen. A similar response was observed in the determinations of interleukin-2 in the supernatants of Con A-stimulated spleen cells from infected mice. When spleen cells from E. histolytica-infected mice were stimulated with phorbol myristate acetate plus ionomycin, results indicated a signal-transduction defect. These alterations, observed at the cellular level, might facilitate invasion of the host by the parasite.
PMID: 7567905 [PubMed - indexed for MEDLINE]
Microb Pathog. 1987 Apr;2(4):241-8.
Immunosuppression and splenomegaly in Entamoeba histolytica infection in mice.
Montreal General Hospital Research Institute, McGill University, Montreal, Quebec, Canada.
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.
PMID: 2907086 [PubMed - indexed for MEDLINE]
Trans R Soc Trop Med Hyg. 1985;79(5):618-23.
Lymphocyte subpopulations transformation studies in an experimental model of intestinal and hepatic amoebiasis.
The lymphocyte subpopulations in peripheral blood and blast transformation were studied on days 0, 3, 7, 11, 15, 20 and 35 after infection in progesterone-treated guinea-pigs which had been experimentally infected with Entamoeba histolytica by intracaecal inoculation. In animals with intestinal infection, lowered T cell numbers and blast transformation were seen during the acute phase with a subsequent tendency to recover. In guinea-pigs with hepatic amoebiasis, both these parameters were significantly depressed throughout the period of study with no tendency to recovery. In progesterone-treated and sham-operated animals, a less marked depression of T cells, was observed. The B cell population did not vary greatly in either group. This study has thus shown that in hepatic amoebiasis there is highly significant depression in both number and function of T cells in comparison to intestinal amoebiasis.
PMID: 3879396 [PubMed - indexed for MEDLINE]