Fu L X, Magnusson Y, Bergh C H, Liljeqvist J A, Waagstein F, Hjalmarson A, Hoebeke J
Wallenberg Laboratory, Sahlgren's Hospital, University of Göteborg, Sweden.
J Clin Invest. 1993 May;91(5):1964-8. doi: 10.1172/JCI116416.
A peptide corresponding to the sequence 169-193 of the second extracellular loop of the human muscarinic acetylcholine receptor-2 was used as an antigen to screen sera from patients with idiopathic dilated cardiomyopathy (DCM, n = 36) and healthy blood donors (HBD, n = 40). The sera from 14 patients with DCM (38.8%) and 3 HBD (7.5%) recognized the muscarinic receptor peptide at dilutions varying from 1:20 to 1:160 in ELISA. A highly significant correlation (P = 0.006) was found between the presence of antimuscarinic receptor-2 autoantibodies and anti-beta-adrenoceptor-1 autoantibodies in the patients' sera. Affinity-purified autoantibodies from positive sera of patients with DCM recognized on the electrotransferred protein of rat ventricular membrane a major band of about 80 kD. Incubation of autoantibodies with membrane resulted not only in a decrease in the maximal binding sites (Bmax) but also in an increase in Kd of radioligand binding in a concentration-dependent manner. This suggests a mixed-type of inhibition. Moreover, preincubation with atropine abolished the inhibitory effect of autoantibodies on the receptor binding whereas carbachol appeared to have no effect on the activity of the autoantibodies. These data define a subgroup of patients with idiopathic DCM who have in their sera functionally active autoantibodies against muscarinic receptor-2.
一种对应于人毒蕈碱型乙酰胆碱受体2第二个细胞外环序列169 - 193的肽被用作抗原，以筛选特发性扩张型心肌病患者（DCM，n = 36）和健康献血者（HBD，n = 40）的血清。在ELISA中，14例DCM患者（38.8%）和3例HBD（7.5%）的血清在1:20至1:160的稀释度下能识别毒蕈碱受体肽。在患者血清中，抗毒蕈碱受体2自身抗体和抗β - 肾上腺素能受体1自身抗体的存在之间发现了高度显著的相关性（P = 0.006）。从DCM患者阳性血清中亲和纯化的自身抗体在大鼠心室膜的电转移蛋白上识别出一条约80 kD的主要条带。自身抗体与膜孵育不仅导致最大结合位点（Bmax）减少，而且以浓度依赖的方式导致放射性配体结合的解离常数（Kd）增加。这表明是一种混合型抑制。此外，用阿托品预孵育可消除自身抗体对受体结合的抑制作用，而卡巴胆碱似乎对自身抗体的活性没有影响。这些数据定义了一组特发性DCM患者，他们的血清中存在针对毒蕈碱受体2的功能活性自身抗体。
