Among 557 NPC tissues, high stromal PD-L2 expression was positively correlated with the infiltration of CD68+ macrophages (51.52 ± 24.41/HPF vs. 42.33 ± 22.74/HPF, Pearson correlation=0.181; P<0.0001) and CD4+Foxp3+ Treg cells (7.49 ± 3.8/HPF vs. 6.96 ± 4.59/HPF, Pearson correlation=0.098; P=0.021; Table 5) in stromal tissue. Here, CD4 is linked to nasopharyngeal carcinoma.