Figure 2.

Pattern of tumor-infiltrating immune cells in the human papillomavirus (HPV)-negative and HPV-associated head and neck squamous cell carcinoma (HNSCC) microenvironments. Although myeloid cells prevail in the HPV-negative tumor microenvironment, HPV-associated tumors are mostly characterized by high numbers of tumor-infiltrating lymphocytes. Neutrophils and myeloid-derived suppressor cells (MDSCs) are not included, as it was not possible to extrapolate the relative proportions of these cell populations from published data.