CD4 and Chagas disease: Although there is no clear evidence for the effector function of this cell population in Chagas' disease, we observed a high percentage of CD25High CD4+ T cells from cardiac patients expressing CTLA-4, as well as an increase in the frequency of CD25High CD4+ T cells expressing IL-10 (Figure 1) with a simultaneous decrease in the frequency of IL-10 receptor in IND and CARD (Figure 2F).