CD4 and gastrointestinal stromal tumor: We analyzed the correlations between PD-L1 expression and clinicopathological features in the 507 GIST patients, and found that PD-1 expression was correlated with tumor location (P = 0.048), mitotic index (P = 0.007), CD3+ (P <0.001), CD4+ (P <0.001), CD8+ (P <0.001), Foxp3+ T cell (P <0.001), CD20+ B cell (P <0.001), CD56+ NK cell (P = 0.006), CD68+ macrophages (P <0.001), and PD-L1 (P <0.001).