中和抗体识别短肽对IFN-α生物学活性的影响

Influence of the synthetic peptide recognized by neutralizing antibody on IFN induced biological responses

目的研究合成肽ＷＬＤＰＲＨ的免疫反应性和对干扰素（ＩＦＮ）诱导的生物学活性的影响。方法根据我们早先的研究，已用中和抗体从噬菌体展示６肽库中筛选出了两个与ＩＦＮ－α有同源性的肽片段，将其中之一进行了人工合成（ＷＬＤＰＲＨ），并进行了同源性比较分析，体外竞争酶联免疫吸附实验（ＥＬＩＳＡ），体外ＩＦＮ诱导抗病毒和抗增殖分析。结果计算机分析表明，人工合成肽ＷＬＤＰＲＨ与推理的Ｉ型ＩＦＮ受体结合区ＬｏｏｐＡＢ（２９－３５位）有相当的同源性。体外竞争ＥＬＩＳＡ实验表明，合成肽在２５μｇ／ｍｌ浓度时能特异性抑制ＩＦＮ－α与中和抗体４Ｃ１结合。体外抗病毒结果显示，干扰素在亚保护剂量时（２０～７０ｐｇ／ｍｌ）时，合成肽能提高ＩＦＮ－α作用细胞后的抗病毒活性，并且合成肽ＷＬＤＰＲＨ在１．４μｇ／ｍｌ时，ＩＦＮ－α抗病毒保护率从４０％提高到８６％，为最高保护率的最低剂量，但合成肽为１．４μｇ／ｍｌ，ＩＦＮ浓度为５～５５ｎｇ／ｍｌ时，对ＩＦＮ－α诱导的抗增殖作用不明显。结论用中和抗体筛选的短肽ＷＬＤＰＲＨ能影响ＩＦＮ分子作用模式，并且有可能模拟ＩＦＮ分子ＬｏｏｐＡＢ的结构和功能，这为免疫治疗及ＩＦＮ的小分子模拟设计奠定基础。

Objective The influence of synthetic peptide WLDPRH on IFN-induced biologic activity was studied.Methods Based on our earlier studies in which two peptides were recognized by neutralizing antibody from the hexapeptide library displayed on the phage, one of the peptides synthesized, with amino acid sequence WLDPRH.Results Computer building approach showed that the synthetic peptide WLDPRH exhibited structural homology with LoopAB (29 35), the binding domain of type I IFN receptor. In the competitive ELISA studies, the synthetic peptide WLDPRH in 25 μg/ml could inhibit IFN binding neutralizing antibody 4C1. IFN induced antiviral assay showed that the protective effects of suboptimal dose (20 70 pg/ml) of IFN were increased from 40% to 86% in the presence of the synthetic peptide WLDPRH and 1.4 μg/ml of the synthetic peptide WLDPRH was the lowest dose with the best protection. But potentiating effect on IFN induced growth inhibition was fewer noticeable in 1.4 μg/ml of synthetic peptide.Conclusion The results indicated that synthetic peptide WLDPRH can mimic the structure and activity of Loop AB in the IFN molecule and can be applied to immunotherapy as well as the mimic minimolecular design of IFN.