Volkmann M, Martin L, Bäurle A, Heid H, Strassburg C P, Trautwein C, Fiehn W, Manns M P
Zentrallabor, Medizinische Klinik und Poliklinik, Universität Heidelberg, Deutsches Krebsforschungszentrum, Heidelberg, Germany.
Hepatology. 2001 Mar;33(3):591-6. doi: 10.1053/jhep.2001.22218.
Autoantibodies to soluble liver antigen (SLA) are considered a specific marker of autoimmune hepatitis. We have performed immunoscreening of a human liver gene expression library with an anti-SLA-positive serum. A reactive clone with a 35-kd open reading frame (ORF) and a 563 base pair (bp) 3' untranslated region (UTR) was isolated (soluble liver antigen [SLA]-p35), showing strong homology to an independently isolated putative SLA/liver-pancreas antigen (LP) sequence (Acc. No. AF146396), and a UGA serine tRNA-protein complex (tRNP)((Ser) Sec) related protein (AJ238617), as well as different expression sequence tag (EST)-clones from lymphatic and oncofetal tissues. Expressed in Escherichia coli, SLA-p35 showed dose-dependent and complete blocking of reactivity to native SLA antigen after preabsorption with the 35-kd recombinant protein. It recognized 67/85 (78.8%) precharacterized anti-SLA-positive sera in dilutions up to 1:40,000 in immunoblot, without detectable cross reactivity in the controls. The commercially available SLA/LP enzymelinked immunosorbent assay (ELISA), by comparison, recognized 63/85 samples (74.1%). Of the negative samples, 18% showed strong inhibition rates (80% and above) in the polyclonal inhibition ELISA. We conlude that the complementary DNA now isolated by 3 independent approaches encodes for the major but not sole antigenic component of soluble liver antigen. Although its truncated form presented here may serve to improve diagnostics based on the new recombinant polypeptide, it currently cannot fully replace the polyclonal inhibition ELISA.
可溶性肝抗原（SLA）自身抗体被认为是自身免疫性肝炎的特异性标志物。我们用抗SLA阳性血清对人肝基因表达文库进行了免疫筛选。分离出一个具有35kd开放阅读框（ORF）和563个碱基对（bp）3'非翻译区（UTR）的反应性克隆（可溶性肝抗原[SLA]-p35），它与一个独立分离的推定SLA/肝-胰腺抗原（LP）序列（登录号AF146396）、一个UGA丝氨酸tRNA-蛋白质复合物（tRNP）（（Ser）Sec）相关蛋白（AJ238617）以及来自淋巴和肿瘤胎儿组织的不同表达序列标签（EST）克隆具有高度同源性。在大肠杆菌中表达后，SLA-p35在用35kd重组蛋白预吸收后对天然SLA抗原的反应性表现出剂量依赖性和完全阻断。在免疫印迹中，它在高达1:40,000的稀释度下识别67/85（78.8%）预先鉴定的抗SLA阳性血清，在对照中未检测到交叉反应性。相比之下，市售的SLA/LP酶联免疫吸附测定（ELISA）识别63/85个样本（74.1%）。在阴性样本中，18%在多克隆抑制ELISA中显示出强抑制率（80%及以上）。我们得出结论，目前通过3种独立方法分离的互补DNA编码可溶性肝抗原的主要但非唯一抗原成分。尽管这里呈现的其截短形式可能有助于基于新的重组多肽改进诊断，但它目前不能完全替代多克隆抑制ELISA。
