In the early phases of persistent stimulation, exhausted T cells (PD-1+CTLA-4+TIM-3+...) can be rescued principally if they express a further TF, the TCF1 encoded by the TCF7 gene: TCF1high cells express the master TF for IFN-γ production T-bet, at a level enough for producing moderated levels of IFN-γ (partially-exhausted T cells), although not at the levels observed in resolving infections, and may hence contribute to maintain the state of chronic low-level inflammation (53–57). Here, PDCD1 is linked to infection.