PDCD1 and infection: Upon infection (d8), Programmed cell death ligand 1 (PD-L1; Cd274) on AM, BECs, DCs, Fibro, iMOs, Macros, ncMOS and Neutros appear to interact with Programmed cell death protein 1 (PD-1; Pdcd1) on Teff, Treg cells and dying T cells, in an attempt to inhibit T cell proliferation, cytokine production and cytotoxicity (Fig 7B) [40,41].