Impact of tumor staging at diagnosis on HPV-16–specific T cell reactivity in OPC patients. (A and B) Box-and-whisker plots showing IFN-γ⁺ CD8⁺ (A) and IFN-γ⁺ CD4⁺ (B) responses against individual HPV-16 antigens in OPC patients with stage I disease (n = 17), stage II disease (n = 35), and stage III disease (n = 10). (C) OPC patients were divided into groups based on their CD8⁺ or CD4⁺ response against one, two, and three or more HPV-16 antigens. A cutoff of 1% IFN-γ⁺ was used for this analysis, and patients were grouped according to their pretherapy or post-therapy status at the time of blood collection. *, P < 0.05; **, P < 0.01; ***, P < 0.001, ns, not significant. The Mann–Whitney U test was performed to calculate significance.