新一期英国《自然—免疫学》（Nature Immunology）杂志刊登报告说，维生素D不仅是身体生长发育所必需的，在免疫方面也发挥着重要作用，它是免疫细胞T细胞对异物发动攻击的“司令员”。
丹麦哥本哈根大学研究人员报告说，免疫系统中的T细胞具有识别并攻击细菌和病毒等异物的功能，但它平时并不处于“战斗状态”，需要得到一个“攻击信号”才能完成从不活跃状态到活跃状态的转换。维生素D就在这个过程中扮演了“司令员”的角色。这次的研究发现，如果没有维生素D，T细胞就算探测到异物也不会采取行动，依然处于不活跃状态。
研究人员说，这一发现说明，可以通过调节体内维生素D含量来控制免疫反应。比如，免疫功能弱的人可以通过补充维生素D来增强抗病能力；而在进行器官移植等手术后，则可以通过减少体内维生素D含量，来减少排异反应。
维生素D存在于鱼类、鸡蛋等天然食物中，多晒太阳也有助于人体合成维生素D。维生素D通过调节体内钙、磷等元素的代谢来维持骨骼、牙齿的正常生长发育。（来源：新华网 黄堃）
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《自然—免疫学》发表论文摘要（英文）
Vitamin D controls T cell antigen receptor signaling and activation of human T cells
Nature Immunology
Volume: 11, Pages: 344–349 Year published:(2010)
doi:10.1038/ni.1851
Received 30 November 2009 Accepted 08 February 2010 Published online 07 March 2010
Phospholipase C (PLC) isozymes are key signaling proteins downstream of many extracellular stimuli. Here we show that naive human T cells had very low expression of PLC-γ1 and that this correlated with low T cell antigen receptor (TCR) responsiveness in naive T cells. However, TCR triggering led to an upregulation of ~75-fold in PLC-γ1 expression, which correlated with greater TCR responsiveness. Induction of PLC-γ1 was dependent on vitamin D and expression of the vitamin D receptor (VDR). Naive T cells did not express VDR, but VDR expression was induced by TCR signaling via the alternative mitogen-activated protein kinase p38 pathway. Thus, initial TCR signaling via p38 leads to successive induction of VDR and PLC-γ1, which are required for subsequent classical TCR signaling and T cell activation.
