PDCD1 and Patent ductus arteriosus: Intratumoral Cxcr3-Klrg1-tetramer + T cells exhibited elevated PD-1 and Lag-3 (Fig. 1D-F), markers of PDA-specific T cells defective in IFNγ and GzmB [8, 25, 28] and consistent with an acquisition of an exhausted T (TEX) cell state.