Luger E, Lamers M, Achatz-Straussberger G, Geisberger R, Inführ D, Breitenbach M, Crameri R, Achatz G
Department of Genetics and General Biology, Institut für Genetik, Salzburg, Austria.
Eur J Immunol. 2001 Aug;31(8):2319-30. doi: 10.1002/1521-4141(200108)31:8<2319::aid-immu2319>3.0.co;2-t.
We have studied two aspects of the IgE immune response. First, we have compared the kinetics of the IgE response to the T cell-dependent antigen ph-Ox coupled to ovalbumin with that of the IgG1 response and we have assessed the quality of the IgE response. Second, we have studied the generation of somatic diversity, understood as the combined effect of somatic mutation and the selection of D(iversity) and J(oining) elements, in germinal center B cells at the molecular level, using the germ-line sequence of the prototype anti-ph-Ox heavy chain variable element V(H)Ox1 as reference. We evaluated sequences derived from mu-, gamma 1- and epsilon-variable elements and showed that somatic diversification was different for all isotypes studied. We further compared the IgE responses of wild-type mice with those of mice expressing a truncated cytoplasmic IgE tail (IgE(KVK Delta tail)). IgE(KVK Delta tail) mice showed a more diverse sequence pattern. We corroborated previous results suggesting that short CDR3 regions are indicative for high-affinity antibodies by measuring relative affinities of phage-expressed Fab fragments with prototype long and short CDR3 regions. Therefore, the composition of the antigen-receptor is responsible for the selection process and the expansion of antigen-specific cells, leading to an isotype-specific antibody repertoire.
我们研究了IgE免疫反应的两个方面。第一，我们比较了针对与卵清蛋白偶联的T细胞依赖性抗原ph-Ox的IgE反应动力学与IgG1反应动力学，并评估了IgE反应的质量。第二，我们在分子水平上研究了生发中心B细胞中体细胞多样性的产生，体细胞多样性被理解为体细胞突变以及D（多样性）和J（连接）元件选择的综合效应，以原型抗ph-Ox重链可变元件V(H)Ox1的种系序列作为参考。我们评估了源自μ、γ1和ε可变元件的序列，结果表明，在所研究的所有同种型中，体细胞多样化情况各不相同。我们进一步比较了野生型小鼠与表达截短细胞质IgE尾巴（IgE(KVK Delta tail)）的小鼠的IgE反应。IgE(KVK Delta tail)小鼠表现出更多样化的序列模式。通过测量噬菌体表达的Fab片段与具有原型长和短互补决定区3（CDR3）区域的相对亲和力，我们证实了先前的结果，即短CDR3区域表明抗体具有高亲和力。因此，抗原受体的组成负责选择过程以及抗原特异性细胞的扩增，从而产生同种型特异性抗体库。
