PDCD1 and nonpapillary renal cell carcinoma: In conjunction with our previous findings, which indicate that the effects of exosomal PD-L2 on lymphocytes can be rescued by PD-1 antibody treatment and PD-1 KO (Figs. 3B–D and S6A–D), these results suggest that exosomal PD-L2 primarily exerts its effects within the ccRCC immune microenvironment through binding to PD-1.