To elucidate the roles of PD-L2 in immune regulation, we analyzed the correlation between the expression of stroma and tumor PD-L2 with the number of CD68+ macrophages and CD4+Foxp3+ Treg cells in the tumor and stroma, respectively, which have been implicated in the tumor microenvironment of previous reports 18-19. This evidence concerns the gene CD68 and neoplasm.