Differential infiltration of CD8+ and NK cells in lip and oral cavity squamous cell carcinoma

J Oral Pathol Med (2010) 39 162–167 Background: CD8⁺ and natural killer (NK) cells have been considered the most effective cells in the combat of cancer, contributing to better prognosis and longer survival. Methods: The aim of this study was to evaluate the population of CD8⁺ and NK cells, by immunohistochemistry, in samples of oral cavity squamous cell carcinoma (OCSCC) and lip squamous cell carcinoma (LSCC), leukoplakia, actinic cheilitis, and healthy oral mucosa (control). The relationship of CD8⁺ and NK cells with survival data, lymph node metastasis, tumor size, and proliferative index was also evaluated. Results: The number of peritumoral and intratumoral CD8⁺ and NK cells was significantly higher in LSCC, when compared with control, pre‐malignant lesions, and OCSCC. A higher proportion of peritumoral CD8⁺ cells demonstrated correlation with a lower neoplastic proliferative index. Moreover, patients with OCSCC with a high density of peritumoral CD8⁺ cells showed a tendency towards a longer survival time. Conclusions: The differential CD8⁺ and NK cells infiltration in oral SCC might reflect a distinctive tumor microenvironment with a favorable local cytotoxic immune response against neoplastic cells.