Cellular immunity to Trypanosoma cruzi is mediated by helper T cells (CD4+).

The infection of mice with Trypanosoma cruzi has been used as an experimental model for human Chagas disease, because the murine and human infections have similar acute and chronic phases generating similar immunopathological phenomena. Histopathological studies of murine tissues showed that the inflammatory lesions were small during the acute phase and composed mainly of mononuclear cells. During the chronic phase, cellular infiltrates were clustered in large granulomata consisting of mononuclear and polynuclear neutrophil cells. Characterization of the infiltrating cells by surface markers showed that about 6% were Thyl.2+ T cells, and CD4+(Lyt 1+) T cells (T helper/DTH subset) were more numerous than CD8+(Lyt 2+) T cells. These observations suggest that delayed type hypersensitivity plays a role in the pathology of Chagas disease.