Impact of radiotherapy on peripheral T lymphocytes in hypopharyngeal squamous cell carcinoma

To investigate the impact of radiotherapy (RT) on the distribution and function of peripheral CD8⁺ T lymphocytes in patients with hypopharyngeal squamous cell carcinoma (HPSCC).

A total of 105 HPSCC patients who underwent definitive RT were enrolled. Baseline levels of peripheral immune cells were obtained, and their alteration during RT was evaluated. Flow cytometry was used to analyze T-cell distribution, cytokine secretion, and CD8⁺ T lymphocyte proliferation capacity.

Lymphocyte count significantly decreased following radiation and remained in a low level after 1 year of RT. CD3⁺ T lymphocyte counts decreased significantly, and the CD4⁺/CD8⁺ ratio increased in HPSCC patients following radiation. The secretion of IFN-γ from peripheral CD8+ T lymphocytes was significantly reduced after irradiation, while the secretion of TNF-α and perforin did not change significantly. Furthermore, the proliferation capacity of peripheral CD8⁺ T lymphocytes was decreased following RT.

RT significantly decreased the number of peripheral T lymphocytes and impaired the secretory function and proliferation ability of CD8⁺ T lymphocytes in HPSCC patients. These findings provide insight into the mechanisms underlying the therapeutic effects of RT on HPSCC and have implications for optimizing treatment strategies.