Pelli N, Fensom A H, Slade C, Boa F, Mieli-Vergani G, Vergani D
Institute of Hepatology, University College London Medical School, Chenies Mews, London, UK
Clin Exp Immunol. 1998 Dec;114(3):455-61. doi: 10.1046/j.1365-2249.1998.00754.x.
Anti-liver cytosol 1 autoantibody (LC1) characterizes a severe form of autoimmune hepatitis (AIH), staining the cytoplasm of periportal hepatocytes and targeting an unidentified 60-kD liver cytosolic antigen. To identify its target, we used high-titre anti-LCI+ sera from two patients with AIH to screen 18 cytoplasm enzymes with periportal location by double immunodiffusion (DDI). Both sera gave a broad precipitin line against human liver cytosol, suggesting that they may recognize two distinct antigens, a possibility confirmed by the appearance of two precipitin lines when DDI conditions were optimized (0.8% agarose and 3% polyethylene glycol (PEG)). Experiments by DDI and Western blot (WB) identified a liver cytosolic autoantigen of 50 kD, different from LC1, giving a line of identity with argininosuccinate lyase (ASL). Reactivity to ASL was then investigated by DDI and WB in 57 patients with AIH, 17 with primary biliary cirrhosis (PBC), 15 with chronic hepatitis B virus (HBV) infection, 13 with alphal-antitrypsin deficiency, 17 with Wilson's disease, 18 with extrahepatic autoimmune disorders, and in 48 healthy controls. Anti-ASL was found in 16% of AIH and 23% of PBC patients by DDI and in 14% of AIH, 23% of PBC and 20% of HBV patients by WB. No argininosuccinate was present in the urine of four anti-ASL+ patients tested, excluding an inhibition of enzymatic activity by anti-ASL. The addition of anti-ASL+ serum to human fibroblast cultures induced a significant increase in ASL activity. ASL is a new autoantigen in liver disease and its clinical relevance warrants further investigation.
抗肝细胞溶质1自身抗体（LC1）是自身免疫性肝炎（AIH）的一种严重形式的特征，它使汇管区周围肝细胞的细胞质染色，并靶向一种未明确的60-kD肝细胞溶质抗原。为了确定其靶抗原，我们使用两名AIH患者的高滴度抗LCI+血清，通过双向免疫扩散（DDI）筛选18种位于汇管区周围的细胞质酶。两种血清均产生针对人肝细胞溶质的宽沉淀线，提示它们可能识别两种不同的抗原，当优化DDI条件（0.8%琼脂糖和3%聚乙二醇（PEG））时出现两条沉淀线证实了这一可能性。通过DDI和蛋白质印迹法（WB）实验鉴定出一种50 kD的肝细胞溶质自身抗原，与LC1不同，它与精氨琥珀酸裂解酶（ASL）形成一条同一线。然后通过DDI和WB在57例AIH患者、17例原发性胆汁性肝硬化（PBC）患者、15例慢性乙型肝炎病毒（HBV）感染患者、13例α1-抗胰蛋白酶缺乏症患者、17例威尔逊病患者、18例肝外自身免疫性疾病患者以及48例健康对照者中研究对ASL的反应性。通过DDI在16%的AIH患者和23%的PBC患者中发现抗ASL，通过WB在14%的AIH患者、23%的PBC患者和20%的HBV患者中发现抗ASL。在检测的4例抗ASL+患者的尿液中未检测到精氨琥珀酸，排除了抗ASL对酶活性的抑制作用。将抗ASL+血清加入人成纤维细胞培养物中可导致ASL活性显著增加。ASL是肝病中的一种新自身抗原，其临床相关性值得进一步研究。
