Selective suppression of tumour-immune cytolytic T lymphocytes in mice with chronic Trypanosoma cruzi infections.
Trypanosoma cruzi is the causative agent of Chagas' disease in man, often leading to suppression of T lymphocyte functions; the present study thus considered the effects of infection by T. cruzi on T-dependent immune responses in a murine model, namely, the immune resistance to a syngeneic tumour and a delayed-type hypersensitivity reaction to sheep red blood cells (SRBC). In BALB.B mice infected with T. cruzi, the graft of syngeneic Gross murine leukaemia virus-induced tumour cells leads to an increased incidence of progressive subcutaneous tumours and development of lymphatic leukaemia. This decreased resistance to tumours correlates with a suppression of the generation of tumour-specific cytolytic T lymphocytes (CTL) from the pre-CTL stage. In contrast, clonal expansion and circulation of T cells detected through their ability to locally transfer a delayed-type hypersensitivity (DTH) reaction to SRBC remained normal in T. cruzi-infected mice. However, at the site of the DTH reaction, a decreased availability of phagocytes was observed in T. cruzi-infected mice.
D000818:Animals; D014355:Chagas Disease / Q000150:complications / Q000276:immunology*; D004195:Disease Models, Animal; D006084:Graft Rejection; D006968:Hypersensitivity, Delayed; D007108:Immune Tolerance; D007942:Leukemia, Experimental / Q000209:etiology / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains; D009368:Neoplasm Transplantation; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D014185:Transplantation, Isogeneic