Figure 2

Markers of immune exhaustion increase with protracted sepsis. Flow cytometry revealed an increase in expression of immune exhaustion markers over time in the ICU. A) Monocyte PD-L1 expression was increased in septic patients compared to critically-ill non-septic patients (CINS) patients. In contrast to changes in programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) expression on CD8 T cells during sepsis, there was no change in the expression of PD-L1 during the septic time period. B) Comparison of monocyte PD-L1 expression and human leukocyte antigen-DR (HLA-DR) expression did not show any correlation in patients with sepsis. (C) PD-1 expression increased as PD-L1 expression decreased on CD8 T cells in samples from septic patients over the course of their sepsis, that is, time points A (days 1 to 3), B (days 4 to 7), C (days 8 to 12) and D (days 13 to 21). CD8 T cell PD-1 expression was higher in septic versus critically-ill non-septic patients (CINS). CD8 T cell expression of PD-L1 fell to very low levels at time point D in septic patients compared to CINS patients and at time points A-C in septic patients. P-values in 2A and 2C are comparison of septic samples with CINS for each draw.