Kahn C R, Baird K, Filier J S, Jarrett D B
J Clin Invest. 1977 Nov;60(5):1094-106. doi: 10.1172/JCI108861.
Autoantibodies to the insulin receptor have been detected in the sera of several patients with the Type B syndrome of insulin resistance and acanthosis nigricans. In this study we have used three of these sera (B-1, B-2, and B-3) as probes of the insulin receptor in isolated rat adipocytes. Preincubation of adipocytes with each of the three sera resulted in an inhibition of subsequent [(125)I]insulin binding. 50% inhibition of binding occurred with serum dilutions of 1:5 to 1:7,500. As in our previous studies with other tissues, Scatchard analysis of the insulin-binding data was curvilinear consistent with negative cooperativity. Computer analysis suggested that in each case the inhibition of binding was due to a decrease in receptor affinity rather than a change in available receptor number. In addition to the effects on insulin binding, adipocytes pretreated with antireceptor sera also showed alterations in biological responses. All three sera produced some stimulation of basal glucose oxidation. With serum B-3, maximal stimulation of glucose oxidation occurred at a serum concentration that inhibited binding by only 10-15%, whereas with serum B-2 the dilution curves for inhibition of binding and stimulation of glucose oxidation were superimposable. Serum B-1 behaved as a partial agonist; that is, it inhibited binding more effectively than it stimulated glucose oxidation. Cells pretreated with this serum in a concentration which inhibited binding by 80% also showed a five-fold shift to the right in the dose response of insulin-stimulated glucose oxidation, whereas spermine-stimulated glucose oxidation was unaffected. Serum B-2, which contained the highest titer of antireceptor antibodies, also stimulated 2-deoxy-glucose transport, as well as glucose incorporation into lipid and glycogen. Both the ability of the serum to inhibit binding and stimulate glucose utilization were enriched in purified immunoglobulin fractions and retained in the F(ab')(2) fragment of the IgG. In addition, the bioactivity was blocked by antihuman IgG but not by anti-insulin antibodies. Enzymatic digestion of adipocytes with trypsin resulted in a complete loss of insulin-stimulated bioactivity of serum B-3, but had only minor effects on the glucose oxidation produced by serum B-1 or B-2.These data suggest that the antibodies present in these three sera bind to different determinants on the insulin receptor. Thus, these antibodies may be useful probes of receptor structure and function.
在患有B型胰岛素抵抗综合征和黑棘皮病的数名患者血清中已检测到胰岛素受体自身抗体。在本研究中，我们使用其中三份血清（B - 1、B - 2和B - 3）作为分离的大鼠脂肪细胞中胰岛素受体的探针。用这三份血清中的每一份对脂肪细胞进行预孵育，都会导致随后的[¹²⁵I]胰岛素结合受到抑制。血清稀释至1:5至1:7500时，结合抑制率达50%。正如我们之前对其他组织的研究一样，对胰岛素结合数据进行Scatchard分析呈曲线状，符合负协同性。计算机分析表明，在每种情况下，结合抑制都是由于受体亲和力降低，而非可用受体数量改变。除了对胰岛素结合的影响外，用抗受体血清预处理的脂肪细胞在生物学反应上也有改变。所有三份血清都对基础葡萄糖氧化有一定刺激作用。对于血清B - 3，葡萄糖氧化的最大刺激出现在血清浓度仅抑制结合10 - 15%时，而对于血清B - 2，结合抑制和葡萄糖氧化刺激的稀释曲线是重叠的。血清B - 1表现为部分激动剂；也就是说，它抑制结合比刺激葡萄糖氧化更有效。用该血清以抑制结合80%的浓度预处理的细胞，胰岛素刺激的葡萄糖氧化剂量反应曲线也向右移动了五倍，而精胺刺激的葡萄糖氧化不受影响。血清B - 2含有最高滴度的抗受体抗体，还刺激了2 - 脱氧葡萄糖转运以及葡萄糖掺入脂质和糖原。血清抑制结合和刺激葡萄糖利用的能力在纯化的免疫球蛋白组分中得到富集，并保留在IgG的F(ab')₂片段中。此外，生物活性被抗人IgG阻断，但不被抗胰岛素抗体阻断。用胰蛋白酶对脂肪细胞进行酶消化导致血清B - 3的胰岛素刺激生物活性完全丧失，但对血清B - 1或B - 2产生的葡萄糖氧化只有轻微影响。这些数据表明，这三份血清中存在的抗体与胰岛素受体上不同的决定簇结合。因此，这些抗体可能是受体结构和功能的有用探针。
