PDCD1 and mature T-cell and NK-cell non-Hodgkin lymphoma: The expression of PD-1 in abnormal T-cell population in the tissue biopsy was significantly higher in AITL than that of other PTCL (CD279-BV605 MFI; Mean ± SEM; 6990.0 ± 934.9 vs. 547.3 ± 155.5; p < 0.0001) (Fig. 1j).