Hogan K T, Brown S L
Department of Microbiology, Medical College of Wisconsin, Milwaukee 53226.
Hum Immunol. 1992 Mar;33(3):185-92. doi: 10.1016/0198-8859(92)90070-4.
A panel of cells expressing 68 different mutant HLA-A2 genes was generated by site-directed mutagenesis and DNA-mediated gene transfer in order to define the regions of class I MHC molecules that contribute to the epitopes recognized by mAb. Each of the variant HLA-A2 molecules differed from HLA-A2.1 by a single amino acid substitution. The substitutions were located in both the alpha-helices and beta-strands of the alpha 1 and alpha 2 domains, and included residues that are highly polymorphic and that are conserved. All but five of the variant HLA-A2 molecules were expressed at levels that ranged from approximately 25%-100% the levels found for HLA-A2.1. The remaining five variants had no detectable expression and all involved substitutions at highly conserved residues. Eleven mAbs with specificities that ranged from highly HLA-A2 specific to monomorphic were analyzed for their ability to bind the variant HLA-A2 molecules. The results demonstrate that the binding of five of 11 mAbs could be mapped to the alpha 1 and alpha 2 domains. MA2.1 was the only antibody mapped to the alpha 1 domain. CR11-351 and A2,A28M1 recognized an overlapping epitope at the amino terminal end of the alpha 2-helix, and PA2.1 and BB7.2 recognized an overlapping epitope that includes the carboxy terminus of the alpha 2-helix and a turn on one of the underlying beta-strands. These results demonstrate that positions located on the surface of the molecule, but not within the peptide-binding cleft of the molecule, are important in serological specificities.
通过定点诱变和DNA介导的基因转移，构建了一组表达68种不同突变HLA - A2基因的细胞，以确定I类MHC分子中对单克隆抗体识别的表位有贡献的区域。每个变异的HLA - A2分子与HLA - A2.1仅存在一个氨基酸替换的差异。这些替换位于α1和α2结构域的α螺旋和β链中，包括高度多态和保守的残基。除了5个变异的HLA - A2分子外，其他所有分子的表达水平在HLA - A2.1表达水平的约25% - 100%范围内。其余5个变异体未检测到表达，且所有变异都涉及高度保守残基的替换。分析了11种特异性范围从高度HLA - A2特异性到单态性的单克隆抗体与变异HLA - A2分子结合的能力。结果表明，11种单克隆抗体中有5种的结合可以定位到α1和α2结构域。MA2.1是唯一一种定位到α1结构域的抗体。CR11 - 351和A2,A28M1在α2螺旋的氨基末端识别一个重叠表位，而PA2.1和BB7.2识别一个重叠表位，该表位包括α2螺旋的羧基末端和一条下层β链上的一个转角。这些结果表明，位于分子表面而非分子肽结合裂隙内的位置在血清学特异性中很重要。
