Expression levels of B7-H3 and TLT-2 in human oral squamous cell carcinoma.

The aim of the present study was to investigate the role of immune regulatory molecules B7-H3 [also known as cluster of differentiation 276] and triggering receptor expressed on myeloid cell-like transcript-2 (TLT-2) in patients with oral squamous cell carcinoma (OSCC). Human OSCC samples were obtained from 76 patients (female, 32; male, 44; age range, 23-81 years; median age, 50.9 years) that underwent resection for OSCC at Peking University Shenzhen Hospital (Shenzhen, China) between 2007 and 2010. In addition, control oral mucosal samples were obtained from 76 healthy individuals (female, 36; male, 40; age range, 21-62 years; median age, 45.3 years) during wisdom tooth extraction. Protein and gene expression levels of B7-H3 and TLT-2 were determined by immunohistochemical analysis and reverse transcription-polymerase chain reaction (RT-PCR). In the healthy oral mucosa samples, B7-H3 expression was identified to be weak, while the expression of TLT-2 was only detected sporadically in the cell membrane and cytoplasm. By contrast, the two regulatory molecules were widely expressed in the aforementioned localizations in human OSCC specimens upon immunohistochemical examination. Furthermore, quantitative RT-PCR confirmed the presence of significantly higher B7-H3 and TLT-2 expression levels in OSCC specimens compared with the oral mucosa of healthy individuals. The significantly higher expression levels of B7-H3 and TLT-2 in human OSCC specimens may indicate an inhibitory role of these molecules in the antitumoral immune response. To investigate interactions between these two molecules and individual antitumoral immune response in OSCC patients, prospective clinical studies with an adequate sample size are required.