Radbruch A, Müller W, Rajewsky K
Proc Natl Acad Sci U S A. 1986 Jun;83(11):3954-7. doi: 10.1073/pnas.83.11.3954.
Mouse B lymphocytes can be activated polyclonally by bacterial lipopolysaccharide (LPS) to secrete Ig and perform Ig class switch. In the presence of the T-cell lymphokine B-cell differentiation factor, the frequency of IgG1-secreting cells is drastically enhanced. We show here that IgG1-secreting B cells isolated from such cultures have undergone a similar DNA rearrangement of the switch regions (S mu, S gamma 1) of the Ig heavy chain constant region genes C mu and C gamma 1 on both active and inactive IgH loci. This result argues against a stochastic model of class switch recombination and suggests programmed class-specific switch recombination in the case of the switch to IgG1. In accord with this notion, cells expressing IgM but not IgG on the surface have not deleted or rearranged C mu or S gamma 1 on either chromosome.
小鼠B淋巴细胞可被细菌脂多糖（LPS）多克隆激活，从而分泌免疫球蛋白（Ig）并进行Ig类别转换。在T细胞淋巴因子B细胞分化因子存在的情况下，分泌IgG1的细胞频率会大幅提高。我们在此表明，从这类培养物中分离出的分泌IgG1的B细胞，在活性和非活性IgH基因座上，Ig重链恒定区基因Cμ和Cγ1的转换区（Sμ、Sγ1）都经历了类似的DNA重排。这一结果与类别转换重组的随机模型相悖，并表明在转换为IgG1的情况下存在程序性的类别特异性转换重组。与此观点一致的是，表面表达IgM但不表达IgG的细胞，在任何一条染色体上都未缺失或重排Cμ或Sγ1。
