Overexpression of CD47 in human HNSCC is associated with inhibitory checkpoints and suppressive immune cell. (A) Representative immunohistochemical staining of CD47, PD-1, PD-L1, Foxp3, CD11b and CD33 in human HNSCC specimens. Scale bar, 25 μm. (B) The expression of CD47 was positively correlated with PD-1 (P<0.001, r = 0.2715) and PD-L1 (P <0.01, r = 0.2527). (C) The expression of CD47 were positively correlated with Foxp3 (P<0.001, r = 0.2857), CD11b (P<0.01, r = 0.2424) and CD33 (P<0.01, r = 0.2154) in human HNSCC. (D) Hierarchical clustering indicated a close relation of CD47 with PD-1 in primary HNSCC. (statistic including 165 primary HNSCC).