Establishment and validation of a tumor-infiltrating γδT cell related prognostic gene signature in head and neck squamous cell carcinoma

γδT cells are unconventional T cells only accounting for 1–5 % of circulating T lymphocytes. Their potent anti-tumor capability has been evidenced by accumulating studies. However, the prognostic value of γδT cells remains not well documented in head and neck squamous cell carcinoma (HNSCC). In this study, we utilized the TCGA HNSCC database to evaluate the infiltration of γδT cells and the association between γδT cells and clinicopathological factors by related gene signature, which were then validated by a total of 100 collected tumor samples from HNSCC patient cohort. Heterogeneity and functional characteristics of distinct infiltrating γδT cell profiles in HNSCC were then investigated based on the scRNA-seq data from the GEO database. We found higher γδT cell gene signature score was significantly associated with longer survival. Cox regression models showed that γδT cell gene signature could serve as an independent prognostic indicator for HNSCC patients. A high level of γδT cell-related gene signature was positively correlated with the infiltration of tumor-infiltrating lymphocytes and immune score. Through scRNA-seq analysis, we identified that γδ+ Trm cells and γδ+ CTL cells possessed anti-tumor and immunoregulatory properties. Notably, we found a significant association between the presence of these cells and improved survival outcomes. In our cell–cell communication analyses, we identified that γδT cells have the potential to eliminate tumor cells through the secretion of interferon-gamma and granzyme. Collectively, the infiltration of γδT cells may serve as a promising prognostic tool, prompting the consideration of treatment options for patients with HNSCC.