IFNG and mature T-cell and NK-cell non-Hodgkin lymphoma: We then evaluated the immune system‐mediated antitumor effects of PD‐1 (+) and PD‐1 (−) cells derived from 5 patients with PTCL, the results showed that IFN‐γ was markedly raised in the supernatants of PD‐1 (−) cells when compared to PD‐1 (+) cells (0.9929 ± 0.1479 vs 0.13 ± 0.03391, P = 0.0027, (Figure 3A), meanwhile the cellular cytotoxicity of PD‐1 (−) cells was stronger than PD‐1 (+) cells (32.46 ± 5.33 vs 48.04 ± 3.837, P = 0.0134) (Figure 3B).