Whereas most circulating IFN-γ-producing CD8+ and CD4+ T cells responsive to T. cruzi display a low degree of differentiation (CD27+/CD28+/CD57−/LIR-1−) [8], [16], high differentiated (CD27−/CD28−/CD57+/LIR-1+) CD8+ and CD4+ T cells are increased in the total peripheral T cell compartment of patients with severe cardiomyopathy [8], [15]–[17]. This evidence concerns the gene CD28 and cardiomyopathy.