Petersen C M, Christiansen B S, Jensen P H, Moestrup S K, Gliemann J, Sottrup-Jensen L, Ingerslev J
Department of Clinical Immunology, University Hospital of Aarhus, Denmark.
Eur J Clin Invest. 1988 Apr;18(2):184-90. doi: 10.1111/j.1365-2362.1988.tb02411.x.
Hepatocytes were isolated by application of the two-step collagenase technique to pieces of human liver. 125I-labelled alpha 2-macroglobulin-trypsin complex bound to hepatocytes at 4 degrees C with a half time of approximately 4.5 h. At near equilibrium half of the receptors were saturated at an alpha 2-macroglobulin-trypsin complex concentration of about 60 pmol 1(-1) and the Scatchard plot was linear. Dissociation of the labelled complex was slow (T1/2 = 24 h) at low receptor occupancies. At high receptor occupancies dissociation was biphasic with a rate constant (K-1) for the initial rapid phase of about 2.4 x 10(-2) min-1. Labelled alpha 2-macroglobulin-trypsin complex bound at 4 degrees C was rapidly internalized at 37 degrees C (T1/2 = 1.9 min), and in 3.5 h approximately 10% of the label was released into the medium in a trichloroacetic acid-soluble form. At 37 degrees C, 125I alpha 2-macroglobulin-trypsin was taken up by hepatocytes and trichloroacetic acid soluble radioactivity appeared in the medium following a sigmoidal curve. Similar results were obtained with 125I-pregnancy zone protein-chymotrypsin complex. At 4 degrees C, hepatocytes bound nearly equal amounts of labelled alpha 2-macroglobulin-trypsin and pregnancy zone protein-chymotrypsin complex, and a large excess (100 nmol 1(-1) of one of the macroglobulins could almost completely abolish binding of trace amounts (5-20 pmol 1(-1] of the other. The present findings strongly suggest that the hepatocyte is of major importance for removal of alpha 2-macroglobulin- and pregnancy zone protein-proteinase complex in humans, in agreement with previous results in rats and mice.
采用两步胶原酶技术从人肝组织块中分离出肝细胞。125I标记的α2-巨球蛋白-胰蛋白酶复合物在4℃与肝细胞结合，半衰期约为4.5小时。接近平衡时，一半的受体在α2-巨球蛋白-胰蛋白酶复合物浓度约为60 pmol/L时被饱和，Scatchard图呈线性。在低受体占有率时，标记复合物的解离较慢（T1/2 = 24小时）。在高受体占有率时，解离呈双相性，初始快速相的速率常数（K-1）约为2.4×10-2分钟-1。在4℃结合的标记α2-巨球蛋白-胰蛋白酶复合物在37℃迅速内化（T1/2 = 1.9分钟），3.5小时内约10%的标记物以三氯乙酸可溶形式释放到培养基中。在37℃，125I-α2-巨球蛋白-胰蛋白酶被肝细胞摄取，培养基中出现的三氯乙酸可溶放射性呈S形曲线。125I-妊娠区蛋白-糜蛋白酶复合物也得到了类似结果。在4℃，肝细胞结合的标记α2-巨球蛋白-胰蛋白酶和妊娠区蛋白-糜蛋白酶复合物数量几乎相等，一种巨球蛋白的大量过量（100 nmol/L）几乎可以完全消除另一种微量（5 - 20 pmol/L）的结合。目前的研究结果强烈表明，肝细胞对于人类清除α2-巨球蛋白和妊娠区蛋白-蛋白酶复合物至关重要，这与之前在大鼠和小鼠中的研究结果一致。
