Sanders J, Allen F, Jeffreys J, Bolton J, Richards T, Depraetere H, Nakatake N, Evans M, Kiddie A, Premawardhana L D K E, Chirgadze D Y, Miguel R Núñez, Blundell T L, Furmaniak J, Smith B Rees
FIRS Laboratories, RSR Ltd, Parc Ty Glas, Llanishen, Cardiff, United Kingdom.
Thyroid. 2005 Jul;15(7):672-82. doi: 10.1089/thy.2005.15.672.
Analysis of nine mouse monoclonal antibodies (mAbs) to the thyrotropin receptor (TSHR) with TSH antagonist activity showed that only one of the mAbs (RSR B2) was an effective antagonist of the human thyroid stimulating autoantibody M22. Crystals of B2 Fab were analyzed by x-ray diffraction and a crystal structure at 3.3 A resolution was obtained. The surface charge and topography of the B2 antigen binding site were markedly different from those of the thyroid-stimulating mAb M22 and these differences might contribute to the different properties of the two mAbs. B2 (but not other mouse TSHR-specific mAbs) was also an effective antagonist of thyroid stimulating autoantibody activity in 14 of 14 different sera from patients with Graves' disease. 125I-labeled B2 bound to the TSHR with high affinity (2 x 10(10) L/mol) and patient serum TSHR autoantibodies inhibited labeled B2 binding to the receptor in a similar way to inhibition of labeled TSH binding (r = 0.75; n = 20). Furthermore, labeled B2 binding was inhibited by patient serum TSHR autoantibodies with TSH antagonist activity and also by mouse and human thyroid stimulating mAbs. Overall, mAb B2 is a powerful antagonist of thyroid stimulating autoantibodies (and TSH) thus resembling closely patient serum TSH antagonist TSHR autoantibodies. Furthermore, B2 might have potentially important in vivo applications when tissues containing the TSHR (including those in the orbit) need to be made unresponsive to stimulating autoantibodies.
对九种具有促甲状腺激素（TSH）拮抗剂活性的抗促甲状腺激素受体（TSHR）小鼠单克隆抗体（mAb）进行分析后发现，其中只有一种单克隆抗体（RSR B2）是人类甲状腺刺激自身抗体M22的有效拮抗剂。通过X射线衍射分析了B2 Fab的晶体，并获得了分辨率为3.3 Å的晶体结构。B2抗原结合位点的表面电荷和形貌与甲状腺刺激单克隆抗体M22明显不同，这些差异可能导致这两种单克隆抗体具有不同特性。B2（而非其他小鼠TSHR特异性单克隆抗体）也是14份来自格雷夫斯病患者的不同血清中甲状腺刺激自身抗体活性的有效拮抗剂。125I标记的B2以高亲和力（2×10¹⁰ L/mol）与TSHR结合，患者血清TSHR自身抗体抑制标记的B2与受体结合的方式与抑制标记的TSH结合相似（r = 0.75；n = 20）。此外，标记的B2结合受到具有TSH拮抗剂活性的患者血清TSHR自身抗体以及小鼠和人类甲状腺刺激单克隆抗体的抑制。总体而言，单克隆抗体B2是甲状腺刺激自身抗体（和TSH）的强大拮抗剂，因此与患者血清TSH拮抗剂TSHR自身抗体非常相似。此外，当含有TSHR的组织（包括眼眶中的组织）需要对刺激自身抗体无反应时，B2可能具有潜在的重要体内应用价值。
