Wigginton S J, Furtado P B, Armour K L, Clark M R, Robins A, Emara M, Ghaemmaghami A M, Sewell H F, Shakib F
School of Molecular Medical Sciences, Institute of Infection, Immunity and Inflammation, University of Nottingham, Nottingham, UK.
Clin Exp Allergy. 2008 Feb;38(2):313-9. doi: 10.1111/j.1365-2222.2007.02896.x. Epub 2007 Dec 7.
IgE binds to mast cells and basophils via its high-affinity receptor, FcepsilonRI, and cross-linking of FcepsilonRI-bound IgE molecules by allergen leads to the release of allergic mediators characteristic of type I hypersensitivity reactions. Previous work has shown that cross-linking of FcepsilonRI with FcgammaRIIb, an ITIM-containing IgG receptor, leads to inhibition of basophil triggering. 2G10, a chimeric human IgG1 anti-idiotype, has broad reactivity with human IgE and as such has the potential to bind simultaneously to FcepsilonRI-bound IgE, via its Fab regions, and the negative regulatory receptor, FcgammaRIIb, via its Fc region.
To assess the ability of human 2G10 to inhibit anti-IgE and allergen-driven basophil degranulation through cross-linking of FcepsilonRI-bound IgE with FcgammaRIIb.
2G10 was assessed for its ability to bind to FcgammaRIIb on transfected cells and on purified basophils. In the basophil degranulation assay, basophils were purified from peripheral blood of atopic individuals and activated with either anti-IgE or the house dust mite allergen Der p 1, in the presence or absence of human 2G10. Basophil activation was quantified by analysis of CD63 and CD203c expression on the cell surface, and IL-4 expression intracellularly, using flow cytometery.
Human 2G10 was able to bind to FcgammaRIIb on transfected cells and on purified basophils, and induce a dose-dependent inhibition of both anti-IgE and Der p 1-driven degranulation of basophils.
The inhibition of basophil degranulation by the human IgG1 anti-idiotype 2G10 highlights the therapeutic potential of IgE-reactive IgG antibodies in restoring basophil integrity through recruitment of the inhibitory receptor FcgammaRIIb.
IgE 通过其高亲和力受体 FcepsilonRI 与肥大细胞和嗜碱性粒细胞结合，变应原使结合在 FcepsilonRI 上的 IgE 分子发生交联，导致 I 型超敏反应特征性过敏介质的释放。先前的研究表明，FcepsilonRI 与 FcgammaRIIb（一种含免疫酪氨酸抑制基序的 IgG 受体）交联可抑制嗜碱性粒细胞的激活。2G10 是一种嵌合型人 IgG1 抗独特型抗体，与人 IgE 具有广泛的反应性，因此有可能通过其 Fab 区域同时结合到结合在 FcepsilonRI 上的 IgE 以及通过其 Fc 区域结合到负调节受体 FcgammaRIIb 上。
评估人 2G10 通过使结合在 FcepsilonRI 上的 IgE 与 FcgammaRIIb 交联来抑制抗 IgE 和变应原驱动的嗜碱性粒细胞脱颗粒的能力。
评估 2G10 与转染细胞及纯化嗜碱性粒细胞上的 FcgammaRIIb 的结合能力。在嗜碱性粒细胞脱颗粒试验中，从特应性个体的外周血中纯化嗜碱性粒细胞，并在有或无人 2G10 存在的情况下，用抗 IgE 或屋尘螨变应原 Der p 1 进行激活。使用流式细胞术通过分析细胞表面 CD63 和 CD203c 的表达以及细胞内 IL-4 的表达来定量嗜碱性粒细胞的激活。
人 2G10 能够与转染细胞及纯化嗜碱性粒细胞上的 FcgammaRIIb 结合，并诱导对嗜碱性粒细胞抗 IgE 和 Der p 1 驱动的脱颗粒的剂量依赖性抑制。
人 IgG1 抗独特型抗体 2G10 对嗜碱性粒细胞脱颗粒的抑制作用突出了 IgE 反应性 IgG 抗体通过募集抑制性受体 FcgammaRIIb 来恢复嗜碱性粒细胞完整性的治疗潜力。
