Figure 6

Anti-PD-1 and anti-PD-L1 antibodies increase IFN-γ production in sepsis. Peripheral blood mononuclear cells (PBMCs) from septic or critically-ill non-septic (CINS) patients were incubated overnight in media containing isotype control antibody, anti- programmed cell death 1 (−PD-1) or anti- programmed cell death ligand 1 (−PD-L1) antibody. The following morning, cells were stimulated with PMA/ionomycin plus brefeldin for 5 h, washed, immunostained with phenotypic markers to CD3 and CD56, fixed and stained for intracellular interferon (IFN)-γ. Flow cytometric analysis revealed that, compared to inactive isotype control antibody, both anti-PD-1 and anti-PD-L1 antibody caused an increase in the percentage of total lymphocytes and natural killer T (NKT) cells that were IFN-γ positive. Anti-PD-1 had no significant effect in CINS patients while anti-PD-L1 increased IFN-γ in total lymphocytes only. Note that IFN-γ production was higher in CINS patients compared to septic patients when incubated with inactive isotype control antibody. Data are from 15 septic patients (21 data points) throughout their illness - all blood draws. Values shown are mean ± SEM values for all time points. Circles indicate mean per group.