TNF and Sepsis: Experimental studies have demonstrated that increased PD-1/PD-L1 expression on surface of peripheral blood monocytes or macrophages in mice with sepsis may lead to a deterioration in the phagocytic functions, downregulate release of pro-inflammatory cytokines, like IL-6 and TNF-α, and upregulate release of anti-inflammatory cytokines, like IL-10 [12, 35].