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The autoimmune regulator (''AIRE'') is a protein that in humans is encoded by the ''AIRE'' gene. AIRE is a transcription factor expressed in the medulla of the thymus and controls the mechanism that prevents the immune system from attacking the body itself. Each T cell attacks a foreign substance presented within a MHC molecule which it identifies with its receptor. T cells have receptors which are generated by randomly shuffling gene segments. Each T cell attacks a different substance. T cells that attack the body's own proteins are eliminated in the thymus. Medullary thymic epithelial cells (mTEC) express major proteins from elsewhere in the body (so called "tissue-restricted antigens" - TRA), and T cells that respond to those proteins are eliminated through cell death(apoptosis), thus it is thought that ''AIRE'' therefore drives negative selection. The AIRE controls the expression of those thymic epithelial cells in the medulla (inner part) of the thymus. When AIRE is defective, T cells can attack the body, resulting in autoimmune disease. ==Function== In the thymus, the autoimmune regulator causes transcription of a wide selection of organ-specific genes that create proteins that are usually only expressed in peripheral tissues, creating an "immunological self-shadow" in the thymus. It is important that self-reactive T cells that bind strongly to self-antigen are eliminated in the thymus (via the process of negative selection), otherwise they can later bind to their corresponding self-proteins and create an autoimmune reaction. So the expression of non-local proteins by AIRE reduces the threat of the occurrence of autoimmunity later on by allowing for the elimination of auto-reactive T cells that bind antigens not traditionally found in the thymus. Furthermore, it has been found that AIRE is expressed in a population of stromal cells located in secondary lymphoid tissues, however these cells appear to express a distinct set of TRAs compared to mTECs Research in knockout mice has demonstrated that Aire functions through initiating the transcription of a diverse set of self-antigens, such as insulin, in the thymus.〔 This expression then allows maturing thymocytes to become tolerant towards peripheral organs, thereby suppressing autoimmune disease.〔 The AIRE gene is expressed in many other tissues as well. AIRE gene is also expressed in the 33D1+ subset of dendritic cells in mouse and in human dendritic cells. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「autoimmune regulator」の詳細全文を読む スポンサード リンク
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