Kutteh W H, Moldoveanu Z, Prince S J, Kulhavy R, Alonso F, Mestecky J
Mol Immunol. 1983 Sep;20(9):967-76. doi: 10.1016/0161-5890(83)90037-8.
The relationship between synthesis, secretion, and subcellular localization of J-chain, IgM, IgA, and IgG was investigated in cultures of PWM-stimulated human PBL and in lymphoblastoid cell lines. Cells were examined for surface, cytoplasmic, and secreted immunoglobulins (Igs) and J-chain by immunofluorescence and radioimmunoassay (RIA). By these techniques, J-chain was detected in cells that produce polymeric or monomeric Igs. In PWM-stimulated PBL the synthesis of J-chain paralleled the production of Igs. In both PWM-stimulated (for 2 days) and unstimulated PBL, equal proportions of free and disulfide-linked J-chain were found. Increased amounts of intracellular J-chain were produced at later stages in PWM-stimulated PBL and J-chain occurred mostly in a free form. In tissue culture fluids, J-chain was not secreted in a free form but was always disulfide-linked to polymeric Igs. In lymphoblastoid cell lines, J-chain was present in a disulfide-linked form in IgM and IGA producers, but in IgG cells and in an IgM cell line (DAUDI) that did not secrete IgM but expressed it on the cell membrane, intracellular J-chain was present in free form. Although various proportions of polymeric and monomeric IgA were seen in culture fluids from IgA-secreting cell lines, intracellular IgA occurred mostly in a monomeric form. Further studies revealed that the ability to produce polymers was not equally distributed among all cells and might vary according to their content of J-chain and stage of maturation. Subcellular fractionation and subsequent analyses for J-chain and Ig in PWM-stimulated PBL and in IgM or IgG-producing cell lines revealed that these proteins were associated with fractions that contained ribosomes, cell sap, and low molecular weight RNA. In lysates of IgG and J-chain producing cells grown in the presence of 3H-labeled amino acids, intracellular J-chain was not disulfide-linked to IgG.
在经PWM刺激的人外周血淋巴细胞（PBL）培养物以及淋巴母细胞系中，研究了J链、IgM、IgA和IgG的合成、分泌及亚细胞定位之间的关系。通过免疫荧光和放射免疫测定（RIA）检测细胞的表面、细胞质和分泌型免疫球蛋白（Ig）及J链。通过这些技术，在产生聚合型或单体型Ig的细胞中检测到了J链。在经PWM刺激的PBL中，J链的合成与Ig的产生平行。在经PWM刺激（2天）和未经刺激的PBL中，均发现游离型和二硫键连接型J链的比例相等。在经PWM刺激的PBL后期，细胞内J链产量增加，且J链大多以游离形式存在。在组织培养液中，J链并非以游离形式分泌，而是始终通过二硫键与聚合型Ig相连。在淋巴母细胞系中，J链以二硫键连接的形式存在于产生IgM和IgA的细胞中，但在产生IgG的细胞以及一个不分泌IgM但在细胞膜上表达IgM的IgM细胞系（DAUDI）中，细胞内J链以游离形式存在。尽管在来自分泌IgA的细胞系的培养液中可见不同比例的聚合型和单体型IgA，但细胞内IgA大多以单体形式存在。进一步研究表明，产生聚合物的能力并非在所有细胞中均等分布，可能会因其J链含量和成熟阶段而有所不同。对经PWM刺激的PBL以及产生IgM或IgG的细胞系进行亚细胞分级分离并随后分析J链和Ig，结果显示这些蛋白质与含有核糖体、细胞液和低分子量RNA的级分相关。在含有3H标记氨基酸的条件下生长的产生IgG和J链的细胞裂解物中，细胞内J链并未通过二硫键与IgG相连。
