PDCD1 and Sepsis: Experiments involving the extraction of lymphocytes from sepsis patients have revealed that the ability of the T lymphocytes to secrete Interferon gamma (IFNγ) and Tumor Necrosis Factor (TNF) in the spleens of deceased sepsis patients was significantly reduced, while their expression of programmed cell death protein 1 (PD-1) was significantly increased, along with PD1 ligand 1 (PDL1) on macrophages and endothelial cells.