A shared alloantigenic determinant on Ia antigens encoded by the I-A and I-E subregions: evidence for I region gene duplication.
A shared alloantigenic determinant on Ia antigens encoded by the I-A and I-E subregions: evidence for I region gene duplication.
复制标题
DOI：
10.4049/jimmunol.127.6.2488
复制
发表时间：
1981-12
影响因子：
4.4
通讯作者：
A. Bhattacharya;M. Dorf;T. Springer
中科院分区：
文献类型：
--
作者：
A. Bhattacharya;M. Dorf;T. Springer
用异种免疫大鼠脾细胞与NSI骨髓瘤融合制备了两种小鼠Ia抗原单克隆抗体。这些单克隆抗体检测携带H-2b、H-2d、H-2k、H-2r和H-2q单倍型小鼠的B细胞和活化T淋巴细胞上存在的多态性决定因子，但不能检测携带H-2s或H-2r单倍型小鼠的多态性决定因子。抗原位点数目测定显示阳性单倍型可分为2组。携带H-2b、H-2d和H-2q单倍型的小鼠在每个B淋巴细胞中表达大量的抗原位点——4万到8万个，单克隆抗体加补体可以溶解这些小鼠的B细胞。相比之下，携带H-2k和H-2r单倍型的小鼠表达的抗原位点数量较少——每个细胞约5000个。携带后一种单倍型的小鼠脾细胞不能用单克隆抗体和补体裂解。遗传图谱显示，高表达区和低表达区分别位于I-A和I-E亚区。该单克隆抗体检测I-Ab、I-Ad、I-Ed和I-Ek分子的Ia特异性。这些观察结果通过几种不同的实验方法得到证实，即细胞毒性、荧光染色、单克隆抗体结合的竞争性抑制和免疫沉淀的二维凝胶电泳。A b A b和E k E k的亲疏度是5到7 × 10(-9) M-1。抗原决定因子热不稳定，这表明它不是碳水化合物。结果表明，不同亚区编码的Ia抗原具有序列同源性，这可能是祖先基因重复的结果。
Two monoclonal antibodies to mouse Ia antigens were produced by fusion of xenoimmune rat spleen cells with the NSI myeloma. These monoclonal antibodies detect polymorphic determinants present on B cells and activated T lymphocytes from mice carrying the H-2b, H-2d, H-2k, H-2r, and H-2q haplotypes but not from mice carrying the H-2s or H-2r haplotypes. Antigenic site number determinations showed the positive haplotypes can be divided into 2 groups. Mice bearing the H-2b, H-2d, and H-2q haplotypes express a high number--40,000 to 80,000--of antigenic sites per B lymphocyte, and monoclonal antibody plus complement can lyse B cells from these mice. In contrast, mice bearing the H-2k and H-2r haplotypes express a low number of antigenic sites--about 5000 per cell. Spleen cells from mice carrying the latter haplotypes are not lysed with monoclonal antibody and complement. Genetic mapping demonstrated that high and low expression map to the I-A and I-E subregions, respectively. The monoclonal antibodies detect an Ia specificity on I-Ab, I-Ad, I-Ed, and I-Ek molecules. These observations were confirmed using several different experimental approaches, i.e., cytotoxicity, fluorescent staining, competitive inhibition of monoclonal antibody binding, and 2-dimensional gel electrophoresis of immunoprecipitates. The avidity for A alpha b A beta b and E alpha k E beta k is 5 to 7 x 10(-9) M-1. The antigenic determinant is heat labile, which suggests that it is not carbohydrate. The results imply that Ia antigens encoded by distinct subregions share sequence homology, which may be a consequence of ancestral gene duplication.