Figure 7

Anti-PD-1 and anti-PD-L1 antibodies increase IL-2 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 interleukin (IL)-2. 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 CD3 and natural killer T (NKT) cells that were IL-2 positive. Anti-PD-L1 had an effect to increase IL-2 production in total lymphocytes and NKT cells in CINS patients. Note that IL-2 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. Values shown are the mean ± SEM values for all time points. Circles indicate mean per group.