However, CD4+ T cells with cytotoxic activity (CD4 CTLs) characterized by the ability to secrete granzyme B, perforin, and IFN-γ and to kill target cells in an MHC class II–restricted fashion were observed in a range of immune responses (19) and expanded in supercentenarians (20), and their importance in Chagas disease has been recently revealed (21). The gene discussed is CD4; the disease is Chagas disease.