7．制御性T細胞の機能と意義

The role of regulatory T cells in health and disease

制御性T細胞(Treg細胞)は，末梢性免疫寛容を維持するうえで，極めて重要な細胞である．Treg細胞は，自己免疫のみならず，炎症や感染，腫瘍においても，制御作用を発揮している．Treg細胞に特異的に発現しているFoxp3遺伝子は，Treg細胞の分化とともに抑制作用にも不可欠である．Treg細胞の大部分は胸腺で分化したnatural Treg細胞である一方，末梢ナイーブCD4T細胞がFoxp3を発現した細胞をinduced Treg細胞という．Treg細胞を介する抑制の低下が自己免疫疾患の発症にかかわっている可能性があり，注目されている．

Foxp3-expressing regulatory T cells (Treg cells) contribute significantly to the maintenance of peripheral tolerance.　In addition to restraining autoimmunity, Treg cells play roles in the regulation of inflammation, infection and tumor growth.　Foxp3 expression is indispensable for differentiation and suprressor function of Treg cells.　Although most peripheral Treg cells are thymus-derived natural Treg cells (nTreg cells), induced Treg (iTreg cells) cells differentiated from peripheral naïve CD4T cells comprise probably a small portion of the peripheral Treg cells.　More attention is paid to impaired Treg cell-mediated regulation as a possible mechanism in human autoimmune diseases.