Identification and characterization of regulatory T cell subsets infiltrated in human oral squamous cell carcinoma

在口腔中超過95%的惡性腫瘤為口腔鱗狀上皮細胞癌，並且為台灣六大常見侵襲癌症死因之ㄧ，然而，口腔癌的高發生率與咀嚼檳榔的習性有關。人類產生在不同器官或組織的癌症，其疾病起因除了基因毒性和致癌基因突變外，目前免疫編輯(immune-editing)也被視為一個重要的因素。為研究在人類口腔鱗狀細胞腫瘤微環境之內調節性T細胞(Tregs)的分布，利用流式細胞儀直接分析在體內的腫瘤浸潤淋巴細胞(TIL)表現各種調節性T細胞的標記分子。結果顯示，在口腔鱗狀細胞癌病患之腫瘤組織內浸潤CD3+CD4+之淋巴細胞中，CD25+T細胞所佔比例為22.8±8.7%，相對於病患之週邊血液中的比例為7.8 ±5.6 %，此增加具有統計上的意義(p<0.0001)。此外，Foxp3在CD4+CD25+調節性T細胞作用及發展中，是重要的轉錄因子，並且和CD25表現量具有相關性。藉由CD25表現之螢光強度，將腫瘤浸潤及周邊血液中CD4+T淋巴球分為:高度表現CD25和Foxp3細胞亞群(CD25highFoxp3high)、中度表現CD25和Foxp3細胞亞群(CD25intermediateFoxp3intermediate)、低度表現CD25和Foxp3細胞亞群(CD25lowFoxp3low)。CD25low和CD25intermediate細胞亞群分別表現大量、或低量的IL-2及IL-10；然而CD25high細胞亞群幾乎不會表現這兩種細胞激素。另外，也發現有CD4+CD25-Foxp3-之T細胞會分泌IL-10，可能為第ㄧ型調節性T細胞(Tr1)。CD4+CD25+Foxp3high之調節性T細胞，具有抑制自體的CD4+CD25-T細胞增生的能力。在腫瘤基質細胞T細胞混合培養系統中，腫瘤基質細胞可以使增加CD3+T細胞分泌IFN-γ、IL-2、TNF-α，卻不能表現IL-4。因此，本研究發現有不同特性的調節性T細胞亞群，浸潤於口腔鱗狀上皮細胞癌中。Oral squamous cell carcinoma (OSCC) accounts for more than 95% of all malignant neoplasms in the oral cavity, and ranks as the sixth major cause of cancer mortality in Taiwan. The high incidence of oral cancer is associated with the habit of chewing areca nut preparations. In addition to genotoxic effects and oncogenic mutations etc, immune-editing is currently regarded as one of the important etiological elements in human cancers. To investigate the distribution of regulatory T lymphocytes (Tregs) within tumor microenvironment in human oral squamous cell carcinoma (OSCC), the in vivo expressions of various Treg markers on tumor-infiltrating lymphocyte (TIL) was directly examined by flow cytometry. The results indicate that, in TIL, proportion of distinct CD25+ cells in the CD3+CD4+ subset (22.8±8.7%) were enriched relative to that found in PBMC (7.8 ±5.6 %) from OSCC patients (p