Introduction: Studies on the role of programmed death-1(PD-1) and its main ligand (PD-L1) during experimental models of sepsis have shown that the PD-1/PD-L1 pathway plays a pathologic role in altering microbial clearance, the innate inflammatory response and accelerated apoptosis in sepsis. However, the expression of PD-1 and PD-L1 and their role during the development of immune suppression in septic patients have not been elucidated. Th e present study was designed to determine whether the expression of PD-1 and PD-L1 is upregulated in septic shock patients and to explore the role of this pathway in sepsis-induced immunosuppression.Methods: Nineteen septic shock patients and 22 sex-matched and age-matched healthy controls were prospectively enrolled. Apoptosis in lymphocyte subpopulations and PD-1/PD-L1 expression on peripheral T cells, B cells and monocytes were measured using flow cytometry. Apoptosis of T cells induced by TNFα or T-cell receptor ligation in vitro and effects of anti-PD-L1 antibody administration were measured by flow cytometry. CD14 + monocytes of septic shock patients were purified and incubated with either lipopolysaccharide, anti-PD-L1 antibody, isotype antibody, or a combination of lipopolysaccharide and anti-PD-L1 antibody or isotype antibody. Supernatants were harvested to examine production of cytokines by ELISA.Results: Compared with healthy controls, septic shock induced a marked increase in apoptosis as detected by the annexin-V binding and active caspase-3 on CD4 + T cells, CD8 + T cells and CD19 + B cells. Expression of PD-1 on T cells and of PD-L1 on monocytes was dramatically upregulated in septic shock patients. PD-1/PD-L1 pathway blockade in vitro with anti-PD-L1 antibody decreased apoptosis of T cells induced by TNFα or T-cell receptor ligation. Meanwhile, this blockade potentiated the lipopolysaccharide-induced TNFα and IL-6 production and decreased IL-10 production by monocytes in vitro.Conclusions: The expression of PD-1 on T cells and PD-L1 on monocytes was upregulated in septic shock patients. The PD-1/PD-L1 pathway might play an essential role in sepsis-induced immunosuppression. © 2011 Zhang et al.; licensee BioMed Central Ltd.
Zhang, Y., Li, J., Lou, J., Zhou, Y., Bo, L., Zhu, J., … Deng, X. (2011). Upregulation of programmed death-1 on T cells and programmed death ligand-1 on monocytes in septic shock patients. Critical Care, 15(1). https://doi.org/10.1186/cc10059