Trypanosoma cruzi modulates the profile of memory CD8 super(+) T cells in chronic Chagas' disease patients

We present a cross-sectional analysis of the maturation and migratory properties of the memory CD8 super(+) T cell compartment, in relation to the severity of heart disease in individuals with chronic Trypanosoma cruzi infection removed from endemic areas for longer than 20 years. Subjects with none or mild heart involvement were more likely to mount T. cruzi-specific memory IFN- gamma responses than subjects with more advanced cardiac disease, and the T. cruzi-specific CD8 super(+) T cell population was enriched in early-differentiated (CD27 super(+)CD28 super(+)) cells in responding individuals. In contrast, the frequency of CD27 super(+)CD28 super(+)CD8 super(+) T cells in the total memory CD8 super(+) T cell population decreases, as disease becomes more severe, while the proportion of fully differentiated memory (CD27 super(-)CD28 super(-)) CD8 super(+) T cells increases. The analysis of CCR7 expression revealed a significant increase in total effector/memory CD8 super(+) T cells (CD45RA super(-)CCR7 super(-)) in subjects with mild heart disease as compared with uninfected controls. Altogether, these results are consistent with the hypothesis of a gradual clonal exhaustion in the CD8 super(+) T cell population, perhaps as a result of continuous antigenic stimulation by persistent parasites.