Although CD4+ T cells have been demonstrated as an important source of IFN-γ during infection (61, 62) and natural killer (NK) cells may also migrate in response to CXCL9 (63) and express IFN-γ and perforin (64, 65), CD8+ T cells are still the most predominant infiltrated population in the heart (66, 67), leading to the hypothesis that CD8+ T cells may have played a major role in ours findings. The gene discussed is CD4; the disease is infection.