Figure 5.

Low infiltration of lymphocytes in primary head and neck squamous cell carcinoma (HNSCC). (A) Paraffin sections of primary HNSCC tumors stained for CD3⁺/CD8⁺, CD20⁺ or CD56⁺ lymphocytes, or CD68⁺/CD163⁺ macrophages. Consecutive sections of a representative patient are shown (magnification 200×). (B) Number of infiltrating lymphocytes and macrophages quantified by counting infiltrating cells in High power fields of the tumor slides. Total cell numbers/HPF are plotted as mean ± SEM (n = 11 patients). (C) Flow cytometric analysis of natural killer (NK) cell subpopulations (CD56^bright/CD16^+/− and CD56^dim/CD16⁺) of patients’ peripheral blood mononuclear cells (PBMCs) and corresponding tumor tissues. PBMCs from healthy donors served as control. NK cell numbers were calculated and plotted as % of CD45⁺ lymphocytes (n = 9 patients; n = 4 healthy controls). (D) Corresponding natural killer group 2D (NKG2D) expression levels of NK cell subpopulations plotted as mean fluorescent intensity (MFI) over background (n = 9 patients). Statistical significance was assessed by one-way analysis of variance. ns, non-significant.