Glesner Jill, Vailes Lisa D, Schlachter Caleb, Mank Nicholas, Minor Wladek, Osinski Tomasz, Chruszcz Maksymilian, Chapman Martin D, Pomés Anna
Indoor Biotechnologies Inc., Charlottesville, VA 22903.
University of South Carolina, Columbia, SC 29208; and.
J Immunol. 2017 Feb 1;198(3):1334-1344. doi: 10.4049/jimmunol.1600072. Epub 2016 Dec 30.
Der p 1 and Der f 1 are major allergens from Dermatophagoides pteronyssinus and D. farinae, respectively. An analysis of antigenic determinants on both allergens was performed by site-directed mutagenesis. The analysis was based on the x-ray crystal structures of the allergens in complex with Fab fragments of three murine mAbs that interfere with IgE Ab binding: the two Der p 1-specific mAbs 5H8 and 10B9, and the cross-reactive mAb 4C1. On one hand, selected residues in the epitopes for mAb 5H8 and mAb 4C1 were substituted with amino acids that resulted in impaired Ab binding to Der p 1. On the other hand, an epitope for the Der p 1-specific mAb 10B9, which partially overlaps with mAb 4C1, was created in Der f 1. The mutation of 1-3 aa residues in Der f 1 was sufficient to bind mAb 10B9. These residues form hydrogen bonds with CDRs of the Ab other than H CDR3. This observation unveils an exception to the dominant role of H CDR3 commonly observed in Ag recognition. Overall, this study resulted in the identification of important residues for mAb and IgE Ab recognition in group 1 mite allergens. This information can be used to engineer allergen mutants with reduced IgE Ab binding for immunotherapy.
Der p 1和Der f 1分别是来自粉尘螨和屋尘螨的主要变应原。通过定点诱变对这两种变应原的抗原决定簇进行了分析。该分析基于变应原与三种干扰IgE抗体结合的鼠单克隆抗体Fab片段复合物的X射线晶体结构：两种Der p 1特异性单克隆抗体5H8和10B9，以及交叉反应性单克隆抗体4C1。一方面，用导致抗体与Der p 1结合受损的氨基酸取代了单克隆抗体5H8和单克隆抗体4C1表位中的选定残基。另一方面，在Der f 1中创建了与单克隆抗体4C1部分重叠的Der p 1特异性单克隆抗体10B9的表位。Der f 1中1至3个氨基酸残基的突变足以结合单克隆抗体10B9。这些残基与除H CDR3之外的抗体互补决定区形成氢键。这一观察结果揭示了在抗原识别中通常观察到的H CDR3主导作用的一个例外情况。总体而言，本研究确定了第1组螨变应原中对于单克隆抗体和IgE抗体识别重要的残基。该信息可用于构建具有降低的IgE抗体结合能力的变应原突变体用于免疫治疗。
