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首页> 外文期刊>Molecular and Cellular Biology >Rearrangements and deletions of immunoglobulin heavy chain genes in the double-producing B cell lymphoma I.29.
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Rearrangements and deletions of immunoglobulin heavy chain genes in the double-producing B cell lymphoma I.29.

机译：双重产生B细胞淋巴瘤I.29中免疫球蛋白重链基因的重排和缺失。

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The B cell lymphoma I.29 consists of a mixture of cells expressing membrane-bound immunoglobulin M (IgM) (lambda) and IgA (lambda) of identical idiotypes. Whereas most of the cells express either IgM or IgA alone, 1 to 5% of the cells in this tumor express IgM and IgA simultaneously within the cytoplasm and on the cell membrane (R. Sitia et al., J. Immunol. 127:1388-1394, 1981; R. Sitia, unpublished data). When IgM+ cells are purified from the lymphoma and passaged in mice or cultured, a portion of the cells convert to IgA+. These properties suggest that some cells of the I.29 lymphoma may undergo immunoglobulin heavy chain switching, although it is also possible that the mixed population was derived by a prior switching event in a clone of cells. We performed Southern blotting experiments on genomic DNAs isolated from populations of I.29 cells containing variable proportions of IgM+ and IgA+ cells and on a number of cell lines derived from the lymphoma. The results were consistent with the deletion model for heavy chain switching, as the IgM+ cells contained rearranged mu genes and alpha genes in the germ line configuration on both the expressed and nonexpressed heavy chain chromosomes, whereas the IgA+ cells had deleted both mu genes and contained one rearranged and one germ line alpha gene. In addition, segments of DNA located within the intervening sequence 5' to the mu gene, near the site of switch recombination, were deleted from both the expressed and the nonexpressed chromosomes. Although mu genes were deleted from both chromosomes in the IgA+ cells, the sites of DNA recombination differed on the two chromosomes. On the expressed chromosome, Smu sequences were recombined with S alpha sequences, whereas on the nonexpressed chromosome, Smu sequences were recombined with S gamma 3 sequences.
机译：B细胞淋巴瘤I.29由表达相同独特型的膜结合免疫球蛋白M（IgM）（lambda）和IgA（lambda）的细胞混合物组成。尽管大多数细胞仅表达IgM或IgA，但该肿瘤中有1-5％的细胞同时在细胞质内和细胞膜上表达IgM和IgA（R。Sitia等人，J。Immunol。127：1388 -1394，1981年; R。Sitia，未公开数据）。当从淋巴瘤中纯化出IgM +细胞并在小鼠中传代或培养后，一部分细胞会转化为IgA +。这些性质表明，I.29淋巴瘤的某些细胞可能会经历免疫球蛋白重链转换，尽管混合群体也有可能是由细胞克隆中的先前转换事件衍生而来的。我们对从包含可变比例的IgM +和IgA +细胞的I.29细胞群体分离的基因组DNA以及从淋巴瘤衍生的许多细胞系上进行了基因组DNA印迹实验。结果与重链转换的缺失模型一致，因为IgM +细胞在已表达和未表达的重链染色体上均以种系构型包含重排的mu基因和α基因，而IgA +细胞已删除mu基因和含有一个重排和一个种系α基因。另外，位于mu基因的插入序列5'内的DNA片段在开关重组位点附近，从表达的和未表达的染色体中都删除了。尽管在IgA +细胞的两条染色体上都删除了μ基因，但DNA重组的位点在两条染色体上是不同的。在表达的染色体上，Smu序列与S alpha序列重组，而在未表达的染色体上，Smu序列与S gamma 3序列重组。

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