IL21 and neoplasm: PD-1 is a key coinhibitory receptor that inhibits the killing function of cytotoxic lymphocytes upon engagement with its ligands (PD-L1 or PD-L2).49–53 To evade host immune surveillance, tumor cells take advantage of this inhibitory pathway by overexpressing PD-L1.12,54 γc is a component of the receptors for IL-2, IL-4, IL-7, IL-9, IL-15 and IL-21, which is constitutively expressed on various populations of immune cells.19 In our experiments, we found that the level of γc in TME was negatively correlated with PD-L1.