In vitro studies have shown that tumor-infiltrating γδ T cells inhibit αβ T cell activation via cell-to-cell contact by PD-1/PD-L1 (228), and polyamine blockade therapy has been reported to enhances the antitumor efficacy of PD-1 blockade (231), which indicates that polyamines may affect the immune function of γδT cells through PD-1/PD-L1, thereby inhibiting the activation of αβ T cells, and ultimately promote tumor progression. The gene discussed is CD274; the disease is neoplasm.