Abstract
BACKGROUND: This study analyzed the immunoexpression of programmed death receptor 1 and its ligands in oral cavity squamous cell carcinoma and correlated the findings with histomorphological parameters. MATERIAL AND METHODS: Forty cases of oral cavity squamous cell carcinoma (10 in the floor of the mouth, 10 in the palate, 10 in the lower lip, and 10 in the tongue) were selected. The percentages of cytoplasmic/membrane immunopositivity for programmed death receptor 1 and its ligands in neoplastic and stromal cells were evaluated at the tumor invasion front. RESULTS: Programmed death-ligand 1 presented high immunoexpression in all subsites, especially at the parenchyma level. Compared to floor of the mouth and palate, lower lip and tongue exhibited higher expression of programmed death receptor 1 and programmed death-ligand 2 in parenchymal cells and of programmed death receptor 1 in stromal cells, with statistically significant differences for programmed death receptor 1 expression in lower lip (p<0.05). Tongue presented the highest median percentages of positivity for programmed death-ligand 2, with statistically significant differences when compared to floor of the mouth (neoplastic cells and stromal cells) and lower lip (stromal cells) (p<0.05). Regarding histomorphological aspects, the inflammatory infiltrate appears to be an important factor for the immunoexpression of these proteins in oral cavity squamous cell carcinoma. CONCLUSIONS: The study suggests location-dependent differences in the antitumor immune response to oral cavity squamous cell carcinoma. Inflammatory infiltrate is key to protein immunoexpression. These findings are crucial for developing new immunotherapeutic strategies for oral cancer.