No abstract

e22070 Background: HLA-G is a human non-classical MHC molecule, mainly expressed in the trophoblast whose main function is to suppress immunologic activity that allows maternal tolerance to phoetus. On the other hand, infiltrating regulatory T lymphocytes (Treg) could promote peripheral inmunotolerance fo oncogenic transformation. Methods: We performed real-time PCR in frozen oral cancer specimens from untreated patients who had undergone surgical resection (n=22) and in normal oral mucosa from healthy subjects (n=10). Samples were processed for mRNA extraction and quantification of gene expression was expressed as relative concentration by an endogenous gene. To asses the presence of infiltrating Treg we analysed CTLA-4, Foxp-3, IL-10, TGF-beta, CD4, CD8, CXCR4, CD127 and CD25 and also we determined HLA-G levels. We correlate the expression of immunologic mediators with clinical variables. Results: Patients presented squamous carcinomas of the tongue (n=12) or gum (n=10) and stages ranged from I to IV (stage I=4; II=9; III=4; IV=5). 10 patients presented well-differentiated lesions and the other 12 moderately-differentiated cells. Eight patients received post- surgery chemo and radiotherapy. Our results show that tumor samples had significant higher expression of the CTLA-4, Foxp-3, TGF-beta and CD127 genes than normal tissue. However, those data showed no correlation between the levels of expression and clinico-pathologic variables. When patients were grouped according to tumor size, there was a trend in the way that bigger tumoral lesions expressed relative higher amounts of Treg. By contrast we could not observe an increase of the expression of HLA-G in patients. Conclusions: Our results reveal that there is an increase in the expression of Treg in oral cancer patients. These Treg in tumoral tissues might contribute to the impairment of immunological rejection of the neoplasic transformation. Conversely we have not been able to demonstrate tumoral expression of HLA-G as a strategy to escape from immunosurveyance. Further analysis of this cells and their function is important in order to develop new therapeutic strategies. No significant financial relationships to disclose.