Incefy G S, Ishimura K, Wang J G, Unson C G, Erickson B W
J Immunol Methods. 1986 May 1;89(1):9-17. doi: 10.1016/0022-1759(86)90026-8.
A new radioimmunoassay (RIA) is described for the quantitation of thymosin alpha-1 (alpha-1). The assay employs an antiserum specific for the COOH-terminal half segment 15-28 of alpha-1, synthetic alpha-1-(15-28) as the hormone standard, and a radioiodinated N alpha-acetyltryrosyl-alpha-1-(15-28) as the tracer. Since alpha-1-(1-28) lacks a phenolic ring for direct radioiodination, the N alpha-acetyltyrosyl-alpha-1-(15-28) was synthesized by the solid-phase method. The peptide bears a Tyr in place of Lys in position 14 of the natural peptide. It showed full alpha-1-(15-28) immunoreactivity and its radioiodinated derivative served as tracer in the RIA. An anti-alpha-1-(15-28) antiserum was raised in a rabbit and was shown to recognize alpha-1-(15-28) or its tyrosyl analogue, and the peptide, alpha-1-(1-28). But it did not recognize other thymic hormones or the biologically active segment 32-36 of thymopoietin, or structurally unrelated peptides. It could also detect natural alpha-1 cross-reacting material in the cytoplasm of cultured human thymic epithelial cells as measured by indirect immunofluorescence. In the RIA, as little as 9 pg of alpha-1-(15-28) equivalents in a 50 microliter sample could be detected. In addition, alpha-1-(1-28)-like immunoreactivity was quantitated in 6 human thymus homogenates and ranged from 0.5 to 4.5 ng/mg of protein.
本文描述了一种用于定量胸腺素α-1（α-1）的新型放射免疫分析（RIA）方法。该分析采用对α-1的COOH末端半段15 - 28具有特异性的抗血清，合成的α-1 -（15 - 28）作为激素标准品，以及放射性碘化的Nα-乙酰酪氨酰-α-1 -（15 - 28）作为示踪剂。由于α-1 -（1 - 28）缺乏用于直接放射性碘化的酚环，因此通过固相法合成了Nα-乙酰酪氨酰-α-1 -（15 - 28）。该肽在天然肽的第14位用Tyr取代了Lys。它显示出完全的α-1 -（15 - 28）免疫反应性，其放射性碘化衍生物在RIA中用作示踪剂。在兔体内制备了抗α-1 -（15 - 28）抗血清，结果表明它能识别α-1 -（15 - 28）或其酪氨酰类似物以及肽α-1 -（1 - 28）。但它不识别其他胸腺激素或胸腺生成素的生物活性片段32 - 36，也不识别结构不相关的肽。通过间接免疫荧光法检测，它还能检测培养的人胸腺上皮细胞胞质中的天然α-1交叉反应物质。在RIA中，50微升样品中低至9皮克的α-1 -（15 - 28）等效物都能被检测到。此外，对6份人胸腺匀浆中的α-1 -（1 - 28）样免疫反应性进行了定量，范围为0.5至4.5纳克/毫克蛋白质。
