Niles M J, Matsuuchi L, Koshland M E
Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.
Proc Natl Acad Sci U S A. 1995 Mar 28;92(7):2884-8. doi: 10.1073/pnas.92.7.2884.
The requirements for IgM assembly and secretion were evaluated by introducing a constitutively expressed J-chain cDNA into lymphoid and nonlymphoid cell lines expressing the secretory form of monomer IgM. Assays of cell lysates and supernatants showed that only secretory monomer IgM is required for the synthesis and secretion of hexamer IgM, whereas J chain, as well as the secreted form of monomer, is required for the synthesis and secretion of pentamer IgM. Moreover, J chain facilitates the polymerization process so that pentamer IgM is preferentially synthesized. Other components of the polymerization process were found to be shared by all the cell lines examined, whether the cells were of lymphoid or nonlymphoid origin and had a rudimentary or developed secretory apparatus. These results identify monomer IgM and J chain as the two components that determine the B-cell-specific expression of IgM antibodies and, thus, as the appropriate targets for therapeutic regulation of IgM responses.
通过将组成型表达的J链cDNA导入表达分泌型单体IgM的淋巴细胞系和非淋巴细胞系，评估了IgM组装和分泌的要求。对细胞裂解物和上清液的检测表明，六聚体IgM的合成和分泌仅需要分泌型单体IgM，而五聚体IgM的合成和分泌则需要J链以及单体的分泌形式。此外，J链促进聚合过程，从而优先合成五聚体IgM。发现聚合过程的其他成分在所检测的所有细胞系中都是相同的，无论这些细胞是淋巴细胞系还是非淋巴细胞系来源，并且具有原始的或发达的分泌装置。这些结果确定单体IgM和J链是决定IgM抗体B细胞特异性表达的两个成分，因此，是IgM反应治疗调节的合适靶点。
