人類週邊血、淋巴結及腫瘤中不同調節性T細胞的鑑定與功能分析

Abstract

人類調節性T細胞是多元的群體，能進一步利用多種細胞標誌來區分出表型上或功能性上有所不同的亞群。先前本實驗室的研究中發現，浸潤在口腔鱗狀上皮細胞癌腫瘤的淋巴細胞中，有一群同時表現介白素-17及FOXP3的調節性T細胞存在。若利用化學趨化因子受體CCR6作為標誌，便能將會表現介白素-17的調節性T細胞分選出來，即是CCR6+調節性T細胞亞群。然而，目前對CCR6+及CCR6-調節性T細胞亞群在表型上以及功能上都不甚了解。因此本研究的研究目的便是要從表型及功能上去了解CCR6+及CCR6-調節性T細胞。在健康成人血液中，大多數的調節性T細胞都是CCR6+調節性T細胞。藉由表型分析發現，CCR6+調節性T細胞屬於活化過的作用型或記憶型T細胞。相反的是，大多數CCR6-調節性T細胞是屬於初始調節性T細胞。相較於CCR6-調節性T細胞，CCR6+調節性T細胞擁有較強的免疫抑制活性，而且介白素-10是其免疫抑制功能重要的分子。另外，有一部分的CCR6+調節性T細胞具有表現介白素-17及丙型干擾素的潛力，且能同時表現介白素-10跟介白素-17，或同時表現介白素-10跟丙型干擾素。同樣的，在口腔鱗狀上皮細胞癌病人週邊血、淋巴結、癌轉移淋巴結及腫瘤浸潤淋巴細胞中都可以發現CCR6+及CCR6-調節性T細胞。相較於病人周邊血液單核細胞，腫瘤浸潤淋巴細胞中有顯著較高比例的CCR6+調節性T細胞。然而，相較於來自週邊血液單核細胞的CCR6+調節性T細胞，來自腫瘤浸潤淋巴細胞的CCR6+調節性T細胞擁有較弱的免疫抑制活性，但卻有顯著更高的介白素-17製造能力。總結以上結果，我們可藉由CCR6的表現將人類調節性T細胞進一步區分出表型及功能上相異的雅族群。

Human regulatory T (Treg) cells are a heterogeneous population which can be subdivided into phenotypically or functionally distinct subsets based on the expression of various markers. Previously, we identified a subset of IL-17-producing Treg cells, in tumor-infiltrating lymphocytes (TILs) of oral squamous cell carcinoma (OSCC), and CC chemokine receptor type 6 (CCR6) can be used as a marker to enrich IL-17+ Treg cells by cell sorting. However, the phenotype and the function of CCR6+ and CCR6- Treg cells are largely unknown. The specific aim of this study is to characterize the phenotypic markers and the suppressive function of CCR6+ and CCR6- Treg cells. In peripheral blood mononuclear cells (PBMCs) of healthy adults, CCR6+ Treg cells comprised the major population of the total Treg cells and exhibited activated effector/memory phenotype. In contrast, CCR6- Treg cells were predominantly CD45RA+ naive Treg cells. The CCR6+ Treg cells displayed consistently higher suppressive activity than CCR6- Treg cells partly through an elevated level of IL-10 production. In addition, portion of CCR6+ Treg cells exhibited the potential to express IL-17 or IFN-γ. Similar functional characteristics of CCR6+ or CCR6- Treg cells are well preserved in PBMCs, lymph node cells (LNCs), and TILs from OSCC patients, except that the frequency of CCR6+ Treg cells are significantly increased in TILs. Moreover, CCR6+ Treg cells from TILs possessed significantly higher IL-17 productivity than those from PBMCs. These results suggested that CCR6 marked phenotypically and functionally distinct cell subsets in human Treg cells.