VITAMIN D METABOLISM BY T CELL LYMPHOCYTES

该项目的目的是表征维生素 D 的代谢 由 T 细胞淋巴细胞在体外进行，特别注意生产 1,25-二羟基维生素 D (1,25(OH)2D)，最活跃的代谢物 维生素 D。首席研究员的初步结果 实验室表明，HTLV 转化的脐带血淋巴细胞具有 将 25(OH)D 转化为极性更强的代谢物的能力，该代谢物与 正宗 1,25(OH)2D 使用两种独立的高性能液体 色谱系统并刺激体外骨吸收。 通过气相色谱/质谱鉴定该代谢物为 1,25(OH)2D 光谱分析表明这些转化的淋巴细胞具有 1-α-羟化酶活性。 由于 1,25(OH)2D 是一种有效的刺激剂 破骨细胞骨吸收，增加 1,25(OH)2D 或其他物质的产生 淋巴瘤细胞的维生素 D 代谢物可能在发病机制中发挥作用 破骨细胞骨吸收增加和高钙血症的发生 在这种疾病中。 因此，本研究的目的是使用 HTLV 转化的 淋巴细胞作为体外模型研究维生素 D 的代谢 淋巴细胞以便： 1. 表征 HTLV 产生的维生素 D 代谢物 转化的 T 淋巴细胞，特别注意产生 1,25(OH)2D。 2. 检测外周淋巴细胞对维生素D的代谢情况 患有以淋巴细胞异常为特征的其他疾病状态的患者 功能并改变骨和矿物质代谢。 3. 确定活化的正常淋巴细胞是否有1-α-羟化酶 活动。 4. 表征正常和异常情况下的 1-α-羟化酶活性 淋巴细胞，看看它是否受到与调节淋巴细胞相同的因素的调节 肾1-α-羟化酶活性。 这些研究将决定是否有能力生产 1,25(OH)2D 是所有活化淋巴细胞的一般特性，或者是 感染 HTLV 病毒的淋巴细胞具有独特的特性。 而且， 1-α-羟化酶活性的表征和鉴定 那些调节淋巴细胞1-α-羟化酶活性的因素 提供有关控制维生素 D 的因素的重要信息 正常个体和疾病状态下的新陈代谢 骨骼和矿物质代谢异常。 这些结果也将形成 旨在阐明相关分子机制的研究基础 用于激活淋巴细胞中的 1-α-羟化酶活性。

The purpose of this project is to characterize the metabolism of vitamin D by T-cell lymphocytes in vitro with particular attention to the production of 1,25-dihydroxyvitamin D (1,25(OH)2D), the most active metabolite of vitamin D. Preliminary results from the Principal Investigator's laboratory indicate that HTLV-transformed cord blood lymphocytes have the capacity to convert 25(OH)D to a more polar metabolite which coelutes with authentic 1,25(OH)2D using two separate high performance liquid chromatography systems and stimulates bone resorption in vitro. Identification of this metabolite as 1,25(OH)2D by gas chromatography/mass spectrometry suggest that these transformed lymphocytes have 1-alpha-hydroxylase activity. Since 1,25(OH)2D is a potent stimulator of osteoclastic bone resorption, increased production of 1,25(OH)2D or other vitamin D metabolites by lymphoma cells may play a role in the pathogenesis of the increased osteoclastic bone resorption and hypercalcemia which occur in this disease. Accordingly, the purpose of this study is to use HTLV-transformed lymphocytes as an in vitro model to study the metabolism of vitamin D by lymphocytes in order to: 1. Characterize the metabolites of vitamin D which are produced by HTLV transformed T-lymphocytes with particular attention to the production of 1,25(OH)2D. 2. Examine the metabolism of vitamin D by peripheral lymphocytes in patients with other disease states characterized by abnormal lymphocyte function and altered bone and mineral metabolism. 3. Determine if activated normal lymphocytes have 1-alpha-hydroxylase activity. 4. Characterize the 1-alpha-hydroxylase activity in normal and abnormal lymphocytes to see if it is regulated by the same factors which regulate renal 1-alpha-hydroxylase activity. These studies will determine whether or not the ability to produce 1,25(OH)2D is a general property of all activated lymphocytes or is a unique property of lymphocytes infected with the HTLV virus. Moreover, characterization of this 1-alpha-hydroxylase activity and identification of those factors which regulate lymphocyte 1-alpha-hydroxylase activity will provide important information concerning factors that control vitamin D metabolism both in normal individuals and disease states characterized by abnormal bone and mineral metabolism. These results will also form the basis of studies designed to elucidate the molecular mechanisms responsible for the activation of 1-alpha-hydroxylase activity in lymphocytes.