SIGLEC15 and head and neck squamous cell carcinoma: The results illustrated that LAG3 (p < 1.32e−10), CTLA4 (p < 7.32e−14), CD274 (p < 5.66e−05), HAVCR2 (p < 9.00e−09), TIGIT (p < 5.67e−10), and SIGLEC15 (p < 3.15e−11) were upregulated in WHO grade II compared with WHO grade I of HNSCC (Fig. 5B).