Mean frequencies of CD8+ EGFR-specific T cells in HNSCC patients and healthy controls. Representative dot plots for tetramer staining are displayed (a). Results are displayed in percent (%) for the control staining with FLU- and HIV-specific tetramers, as well as the EGFR-specific pentamer KLF and tetramer YLN. For both EGFR-specific peptides, HNSCC patients with a high EGFR score (> 7) had a significantly elevated frequency of EGFR-specific CTL, compared to patients with low EGFR score (< 7) and normal donors (* p-value < 0.05). No significant difference was seen between normal donors and patients with low EGFR score (b).