CD4 and Chagas disease: Ex vivo data obtained from patients with indeterminate and cardiac clinical forms of Chagas' disease have shown that there is an increased frequency of CD25High CD4+ Treg cells in the peripheral blood of IND patients when compared to CARD and non-infected individuals [9], suggesting that an expansion of CD25High CD4+ Treg cells may be beneficial during the chronic phase of the disease, probably by limiting tissue damage, leading to lifelong persistence of the indeterminate clinical form of Chagas' disease.