Kehoe J M, Seide R K
J Am Vet Med Assoc. 1982 Nov 15;181(10):1000-4.
Recent studies of the molecular biological characteristics of lymphoid cells have markedly increased our understanding of how millions of different antibodies can be synthesized by an individual mammal. In particular, studies have shown how antibody genes are arranged and rearranged within B-lymphocyte clones to provide each cell clone with antibody of defined specificity for antigen. The process involves the assembly, from disparate genetic elements, of a complete antibody gene that will code for an antibody protein. The assembly process, in itself, also provides mechanisms for generating the diversity of antibody variable region structure (that part of an antibody molecule that actually binds antigen) that is essential to a full role for humoral immunity in host defense mechanisms. Specifically, the diversity of structure characteristic of mature antibodies derives from 3 distinct mechanisms: innate variability of germ-line genes; mismatching of individual gene segments during their somatic rearrangement leading to junctional diversity; and somatic mutation in variable region genetic material during or after the rearrangement. Thus, it is now clearly understood that several processes are involved in explaining the origin of the antigen-combining diversity of antibody proteins. Certain "lottery-like" aspects of these genetic processes add to the combinatorial possibilities that are characteristic of the humoral immune system.
最近对淋巴细胞分子生物学特性的研究显著增进了我们对于个体哺乳动物如何能够合成数百万种不同抗体的理解。特别地，研究已经表明抗体基因在B淋巴细胞克隆内是如何排列和重排的，从而为每个细胞克隆提供针对抗原具有特定特异性的抗体。该过程涉及从不同的遗传元件组装一个完整的抗体基因，该基因将编码一种抗体蛋白。组装过程本身也提供了产生抗体可变区结构（抗体分子中实际结合抗原的部分）多样性的机制，这对于体液免疫在宿主防御机制中充分发挥作用至关重要。具体而言，成熟抗体结构多样性源自3种不同机制：种系基因的固有变异性；个体基因片段在体细胞重排过程中的错配导致连接多样性；以及重排期间或之后可变区遗传物质中的体细胞突变。因此，现在已经清楚地认识到，有几个过程参与了解释抗体蛋白抗原结合多样性的起源。这些遗传过程中某些“类似彩票”的方面增加了体液免疫系统特有的组合可能性。
