Despite an increase in Mtb-specific IFN-γ production in both LTBI and smear+ TB groups, we did not observe any significant enhancement of Mtb-specific CD4 T cell proliferative capacity with PD-1/PD-L1 blockade, a function that we and other have previously reported to be impaired in patients with smear+ TB (20, 24, 77). Here, PDCD1 is linked to tuberculosis.