CD4 and heart disorder: IFN-γ nonproducers with cardiac disease (i.e., subjects of the G1, G2 and G3 clinical groups) exhibited lower frequencies of phosphorylated STAT5+ (pSTAT5) in CD4+ T cells than IFN-γ producers and uninfected subjects, in response to IL-7 (Fig 5A, S4A and S4B Fig).