Thymopoietin is a thymic hormone that induces differentiation of thymocytes from precursor cells which arise in hemopoietic tissues. This paper describes a sensitive in vitro assay for the induction of Thy 1.2 antigen on null lymphocytes from germ-free athymic (nuu) mice. The sensitivity and specificity of the bioassay were increased by adding high concentrations of ubiquitin (a nonspecific inducer) to the induction incubations. The bioassay was sufficiently sensitive to detect thymopoietin at less than 0.25 ng/ml. A dose-response relationship was shown between thymopoietin concentration and the percentage of cells induced to express Thy 1.2 antigen. When normal human plasma was assayed, induction was registered with activity corresponding to thymopoietin at greater than 1 ng/ml in plasma from infants or young adults. Activities in the thymopoietin range of 0.25 ng/ml were registered with plasma from healthy subjects over 50 years of age. Thymectomy was followed by loss of this inductive activity from the plasma. This bioassay permits clinical studies on T (thymus-derived) cell inducers released by the human thymus into the circulation.
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机译:胸腺生成素是一种胸腺激素,可诱导胸腺细胞与造血组织中出现的前体细胞分化。本文介绍了一种敏感的体外测定方法,用于从无菌无胸腺(nu / nu)小鼠的无效淋巴细胞上诱导Thy 1.2抗原。通过在诱导培养中添加高浓度的泛素(一种非特异性诱导剂),可以提高生物测定的灵敏度和特异性。该生物测定法足够灵敏,可以检测出低于0.25 ng / ml的胸腺生成素。胸腺生成素浓度与诱导表达Thy 1.2抗原的细胞百分比之间显示出剂量反应关系。当测定正常人血浆时,在婴儿或年轻成人血浆中,对应于胸腺生成素的活性以大于1 ng / ml的活性被记录下来。用来自50岁以上健康受试者的血浆记录的胸腺生成素活性为0.25 ng / ml。胸腺切除术之后,血浆中这种诱导活性丧失。该生物测定法允许对由人胸腺释放到循环中的T(胸腺来源)细胞诱导剂进行临床研究。
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