Expression And Significance Of PD-1/PD-L1 On T Cell And Dendritic Cell In Sepsis

Objective:To study the effect of PD-1/PD-L1 regulating DC on the immune status of sepsis,and analyze the effect of PD-1/PD-L1 on prognosis.Methods:Twenty-five patients with sepsis in the ICU and EICU wards of the Affiliated Hospital of Zunyi Medical University from October 2018 to September2019 were collected and followed up for 28 days.According to the 28-day survival of patients,the survival group and death group were set up.Among them,10 were in the survival group and 15 were in the death group.Simultaneously,20 healthy people were enrolled as the control group.Peripheral blood was collected from patients 24hours after diagnosis.Flow cytometry was used to detect the proportion of CD4~+T and CD8~+T cells,the composition ratio of T cell subsets(CD4/CD8),the expression of PD-1 on CD4~+T and CD8~+T cells and the expression of PD-L1 and CD86 in DC.ELISA was used to detect the levels of IL-10 and TNF-α.Results:There were 25 patients with sepsis,10 patients who survived and 15patients who died,and the mortality rate was 66.7%.The scores of SOFA(Sequential organ failure assessment)and APACHE II(Acute physiology and chronic health Evaluation II)in the death group were higher than that in the survival group(P<0.05).The composition ratio of T cell subsets in the survival group and the death group was<1,the death group was lower than those in the survival group(P<0.05),and the composition ratio of T cell subsets in the control group was>1.The levels of CD4~+T cells in the survival and death groups were lower than those in the control group(P<0.01),and the death groups were lower than those in the survival group(P<0.05).The levels of DC and CD8~+T cells in the control and survival groups were higher than those in the death group(P<0.01),and the levels in the control group and the survival group had no significant changes(P>0.05).The expression of PD-L1 on the surface of DCs in the survival and death groups was higher than that in the control group(P<0.05),and the death group was higher than that in the survival group(P<0.05).The expression of CD86 molecule on DC surface was lower in the survival and the death group than in the control group(P<0.05),and the death group was lower than that in the survival group(P<0.05).The levels of IL-10 and TNF-αin the survival and death groups were higher than those in the control group(P<0.05),and those in the death group were higher than those in the survival group(P<0.05).The expression of PD-1on CD4~+T cells had statistical significance on the prognosis of patients(P<0.05).The expression of PD-1 in CD4~+T cells was positively correlated with the SOFA score,the expression of PD-1 in CD8~+T cells and the expression of PD-L1 in DC(P<0.5).It was negatively correlated with the positive rate of CD4~+T cells and the expression of CD86 in DC(P<0.05).The expression of PD-1 on CD4~+T cells is an independent risk factor for the prognosis of patients(P<0.05),and has a significant predictive value for the death of sepsis patients(P<0.01).The best predictive value is 34.48%,with accuracy 85.7%.Conclusion:Up-regulation of PD-1/PD-L1 in peripheral blood will inhibit the activation and value-added of DC,affect the activation of T cells,and induce the body of sepsis patients to enter an immunosuppressive state.PD-1/PD-L1 can reflect the immune status of patients with sepsis.Among them,the expression of PD-1 on CD4~+T cells may have important significance for the evaluation of patients’prognosis.