An integrative model with HLA‐DR, CD64, and PD‐1 for the diagnostic and prognostic evaluation of sepsis

Abstract Background Sepsis is a life‐threatening organ dysfunction caused by a dysregulated host response to infection and progressive immunosuppression with high mortality. HLA‐DR, CD64, and PD‐1 were assumed to be useful biomarkers for sepsis prediction. However, the ability of a combination of these biomarkers has not been clarified. Methods An observational case‐control study was conducted that included 30 sepsis patients, 30 critically ill patients without sepsis admitted to the intensive care unit (ICU), and 32 healthy individuals. The levels of HLA‐DR, CD64, and PD‐1 expression in peripheral blood immune cells and subsets was assayed on Days 1, 3, and 5, and the clinical information of patients was collected. We compared these biomarkers between groups and evaluated the predictive validity of single and combined biomarkers on sepsis mortality. Results 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. Importantly, the expression of PD‐1+CD4−CD8−T (OR = 0.622, 95% CI = 0.423–0.916, p = .016) and mHLA‐DR+ (OR = 1.146, 95% CI = 1.014–1.295, p = .029) were significantly associated with sepsis mortality. For sepsis diagnosis, the mHLA‐DR+, PD‐1+CD4−CD8−T, and nCD64 index showed the moderate individual performance, and combinations of the three biomarkers achieved greater diagnostic value (AUC = 0.899, 95% CI = 0.792–0.962). When adding PCT into the combined model, the AUC increased to 0.936 (95% CI = 0.840–0.983). For sepsis mortality, combinations of PD‐1+CD4−CD8−T and mHLA‐DR+, have a good ability to predict the prognosis of sepsis patients, with an AUC = 0.921 (95% CI = 0.762–0.987). Conclusion These findings indicate that the combinations of HLA‐DR, CD64, and PD‐1 outperformed each of the single indicator in diagnosis and predicting prognosis of sepsis.