Repertoire of peripheral T cells in patients with oral squamous cell carcinoma

BACKGROUND: The establishment of adaptive immune responses to neoplasms involves not only the tumour tissue, but also the peripheral blood. We aimed to conduct a preliminary exploration to understand the immune response of T lymphocytes of peripheral blood mononuclear cells (PBMC-Ts) in oral squamous cell carcinoma (OSCC). METHODS: A total of 103 blood samples from OSCC patients and 18 blood samples from healthy donors (HD) were analysed by flow cytometry. RESULTS: Compared to those in HD, a series of unique features of PBMC-Ts were observed in OSCC patients including a significant increase in CD4+ T cells, a shift from naive to memory/effector phenotype, an increased frequency of exhausted phenotypes (programmed death-1 [PD-1], T cell Ig and mucin protein-3 [Tim-3] and Tregs), an abundance of Th17s and Tc17s and an imbalance in Th17/Tc17 and Th17/Treg ratios. Furthermore, in OSCC patients, we also found that CD4+ T cells were significantly increased in patients with larger tumours than smaller tumours, memory/effector phenotype and exhausted phenotypes were significantly associated with advanced clinical stage and lymph node metastasis, and the Th17/Treg ratio was associated with early clinical stage and no lymph node metastasis. CONCLUSION: PBMC-Ts may be involved in the development and progression of OSCC, which suggested to be a manifestation of an immune response between host and tumour neoantigens.