The results indicate that PD‐1 expression on CD4−CD8−T (PD‐1+CD4−CD8−T) (19.19% ± 10.78% vs. 9.88% ± 1.79%, p = .004) cells and neutrophil CD64 index (nCD64 index) (9.15 ± 5.46 vs. 5.33 ± 2.34, p = .001) of sepsis patients were significantly increased, and HLA‐DR expression on monocytes (mHLA‐DR+) was significantly reduced (13.26% ± 8.06% vs. 30.17% ± 21.42%, p = 2.54 × 10−4) compared with nonsepsis critically ill patients on the first day. Here, PDCD1 is linked to Sepsis.