Birva V. Brahmbhatt^1,, Hemangini H. Vora¹

Aim: Immunosuppresion in oral squamous cell carcinoma (OSCC) is related to high degree of recurrence and believed to develop from premalignant lesion. Leukocytes especially T cell subsets are important in immune surveillance during malignant transformation. This study has been planned to observe changes in systemic immune response in premalignant and malignant oral lesions. Method: The proportions of Neutrophils, Monocytes, Lymphocytes, total T cells, T cell subsets including αβ/γδ T cells, Cytotoxic T cells, Helper T cells, Naive/ Effector/Memory T cells, Regulatory T cells and NK-T subpopulations were analysed in peripheral circulation of healthy donors (N= 49), Leukoplakia (N=20) and OSCC patients (N=100) by flowcytometry. Results: In comparison with healthy donors, decreased Lymphocytes, Naive Helper cells, NK T subpopulations and increased Effector cells were observed in Leukoplakia patients. Similarly, decreased Lymphocytes, NK T subpopulations and increased Neutrophils, Monocytes, Helper and Regulatory T cells were observed in OSCC patients as compared to healthy controls. Moreover, Lymphocytes were decreased and Regulatory T cells were increaed during the progression of Leukoplakia to OSCC. Further, in relation with clinicopathological parameters, Cytotoxic cells were found to be reduced with increasing histological grade. Also, Helper cells were found to be decreased in patients with tobacco and alcohol habit and also with increasing tumor size. Further, in univariate survival analysis, increased incidence of relapse was observed in patients with low γδ and NK T cells. In multivariate survival analysis, low γδ T cells emerged as poor prognosticator for disease free survival and high Regulatory T cells emerged as poor prognosticator for predicting overall survival. Conclusion: Altered systemic immune response was seen during malignant transformation and also found to be associated with patient’s survival. Thus, investigation of circulating Leukocyte and T cell subsets seems to be useful for predicting patient’s survival and to identify immunosuppressed patients who may be benefited with immunotherapy.

immunosuppresion, OSCC, T cells, flowcytometry