IMMUNOGLOBULIN GENES IN DIFFERENTIATING B CELLS

免疫球蛋白(Ig)基因结构的一系列重要变化 发生在B细胞发育期间。完全变量的两种形式(五) 编码重(H)和轻(H)的恒定(C)区的5‘区 链蛋白及其V-H区与C-H区的后续连接 C区3‘(重链切换)是通过重组发生的 机械装置。然而，因为这些事件在时间上是不同的，并且使用 不同的识别序列，不同的重组系统 可能在每种情况下都会用到。到目前为止，我们的大部分信息都是关于 B过程中H链切换的机理及其时机 细胞分化来自于对骨髓瘤和少数B细胞的研究 肿瘤。 我们最近开发了一个模型系统来研究免疫球蛋白基因结构 用逆转录病毒Abelson病毒诱导成熟B细胞分化。 使用这种方法，我们已经开发出一系列克隆的、永生的、 非致瘤性mIgM和Ig G阳性B细胞株。不同的菌株 合成各种H链和L链亚型，部分菌株分泌Ig。 这些细胞的独特性质及其执行密钥的能力 B细胞发育中的重组步骤使其成为理想的模型系统 B细胞缺失性转换的时机和机制研究 细胞分化。

A series of important changes in the structure of immunoglobulin (Ig) genes occurs during B cell development. Both formation of complete variable (V) regions 5' of the constant (C) regions encoding both heavy (H) and light chain proteins and the subsequent linkage of the V-H region with C-H regions 3' of C (heavy chain switching) occur by recombinatorial mechanisms. However, because these events are temporally distinct and use different recognition sequences, different recombinatorial systems are probably used in each case. To date, most of our information concerning the mechansim of H chain switching and its timing during the course of B cell differentiation has come from studies of myelomas and a few B cell tumors. We have recently developed a model system to study Ig gene structure during differentiation of mature B cells using the retrovirus Abelson virus. Using this approach, we have developed a series of clonal, immortalized, nontumorigenic mIgM and IgG-positive B cell lines. Different isolates synthesize various H and L chain isotypes and some isolates secrete Ig. The unique nature of these cells and their ability to carry out a key recombinatorial step in B cell development make them an ideal model system to study both the timing and the mechanism of deletional switching during B cell differentiation.