Lorenz M, Jung S, Radbruch A
Institute for Genetics, University of Cologne, Germany.
Behring Inst Mitt. 1995 Jun(96):97-102.
B lymphocytes can alter the class of antibody they produce by immunoglobulin class switch recombination. This recombination is targeted by distinct cytokines to particular switch regions. Prior to switch recombination, the same cytokines induce transcription through the targeted switch regions and generate IH "switch" transcripts. To show whether the two events are functionally related, we have replaced the endogenous interleukin-4 (IL-4) dependent promoter of murine I gamma 1 switch transcripts by an heterologous promoter, the human metallothionein IIA (hMT) promoter. Indeed, switch recombination can be targeted to IgG1 by the hMT promoter. In mutant mice, which cannot generate processed switch transcripts, switch recombination cannot be targeted to IgG1 by the hMT promoter. Thus, IL-4 targets switch recombination to IgG1 by induction of processed switch transcripts.
B淋巴细胞可通过免疫球蛋白类别转换重组改变其所产生抗体的类别。这种重组由不同的细胞因子靶向特定的转换区域。在类别转换重组之前，相同的细胞因子通过靶向的转换区域诱导转录并产生IH“转换”转录本。为了证明这两个事件在功能上是否相关，我们用异源启动子——人金属硫蛋白IIA（hMT）启动子取代了小鼠Iγ1转换转录本的内源性白细胞介素4（IL-4）依赖性启动子。实际上，hMT启动子可将类别转换重组靶向IgG1。在无法产生加工后的转换转录本的突变小鼠中，hMT启动子不能将类别转换重组靶向IgG1。因此，IL-4通过诱导加工后的转换转录本将类别转换重组靶向IgG1。
