Mechanistically, at low antigen concentrations the interaction between PD-L2 and PD-1 inhibits strong B7-CD28 signals, while at high concentrations, the interaction between PD-L2 and PD-1 reduces cytokine production, but not T cell proliferation, but the correlation between these PDCD1LG2 SNPs and PD-L2 expression requires further investigation, which might provide further insight into the PD-1/PD-L2 axis in T cell function and lung carcinogenesis (57). The gene discussed is PDCD1LG2; the disease is medical procedure.