Wabl M R, Burrows P D
Proc Natl Acad Sci U S A. 1984 Apr;81(8):2452-5. doi: 10.1073/pnas.81.8.2452.
The major intron between the J and C gene segments of the immunoglobulin heavy (H) chain locus contains an enhancer-like sequence, and it has been proposed that this enhancer is necessary to achieve high levels of H chain expression. We have isolated a subclone of the lymphoid pre-B cell line 18-81 that lacks this enhancer but nevertheless produces mu chain at the level characteristic of pre-B cells. Another subclone with a larger deletion does not produce mu chain, but upon fusion with a myeloma that does not produce any immunoglobulin chain, mu chain is expressed by the homolog from the pre-B subclone. The hybridoma lacks the proposed enhancer element in cis; nevertheless it produces as much mu chain as other plasma cell hybridomas. Therefore, this enhancer element is not obligatory for a high level of H chain production.
免疫球蛋白重（H）链基因座的J基因片段和C基因片段之间的主要内含子包含一个类似增强子的序列，有人提出该增强子对于实现高水平的H链表达是必需的。我们分离出了淋巴前B细胞系18 - 81的一个亚克隆，该亚克隆缺乏此增强子，但仍以前B细胞特有的水平产生μ链。另一个缺失更大的亚克隆不产生μ链，但与不产生任何免疫球蛋白链的骨髓瘤细胞融合后，前B亚克隆同源的μ链得以表达。该杂交瘤在顺式结构中缺乏所提出的增强子元件；然而，它产生的μ链与其他浆细胞杂交瘤一样多。因此，该增强子元件对于高水平的H链产生并非必不可少。
