CD8+ T cells in Trypanosoma cruzi infection.

CD8(+) T cells have emerged as crucial players in the control of a number of protozoan pathogens, including Trypanosoma cruzi, the agent of human Chagas disease. The recent identification of the dominant targets of T. cruzi-specific T cells has allowed investigators to follow the generation of and document the functionality of T cell responses in both mice and humans. Although slow to develop in the early stages of the infection, T. cruzi-specific CD8(+) T cells reach prodigious levels and remain highly functional throughout chronic infections in mice. Following drug-induced cure during either the acute or chronic stage, these immunodominant T cells persist as stable, antigen-independent memory populations. T. cruzi-specific CD8(+) T cells in humans are less-well-studied but appear to lose functionality and decline in numbers in these decades-long infections. Changes in the frequency of parasite-specific T cell upon therapeutic treatment in humans may provide a new metric for determining treatment efficacy.