Parr T B, Johnson T A, Silberstein L E, Kipps T J
Sam and Rose Stein Institute for Research on Aging, Department of Medicine, University of California, San Diego, La Jolla 92093-0663.
Eur J Immunol. 1994 Dec;24(12):2941-9. doi: 10.1002/eji.1830241204.
We isolated immunoglobulin (Ig) VH4 genes that were rearranged in the genomic DNA of 160 day human fetal spleen. Productively rearranged VH 4-21 genes were cloned into pRTM1, a human IgM expression vector. This allowed us to generate IgM kappa-expressing transfectomas by co-transfecting each of these constructs with pSVG-V kappa 3, an Ig kappa light-chain expression vector that has a variable region encoded Humkv325, a conserved V kappa gene that is frequently expressed early B cell ontogeny. We find that all transfectomas expressing IgM kappa encoded by VH 4-21 make IgM autoantibodies reactive with i, a linear poly-N-acetyllactosamine determinant present on neonatal red blood cells and a B cell-restricted isoform of the CD45 surface molecule. In contrast, a transfectoma expressing pSVG-V kappa 3 and pRTM1 containing a rearranged VH4-59 (V71-4) gene isolated from a chronic lymphocytic leukemia B cell population, designated WIL, produced IgM kappa antibodies that had no detectable anti-i binding activity. However, transfectomas expressing VH 4-21 fused onto the Ig heavy-chain third complementarity determining region (CDR3) of WIL are found to make anti-B cell autoantibodies with anti-i activity. These studies indicate that VH 4-21 genes rearranged in human fetal B cell ontogeny can encode anti-B cell autoantibodies with a binding specificity that does not require in vivo somatic selection.
我们从160日龄人类胎儿脾脏的基因组DNA中分离出重排的免疫球蛋白（Ig）VH4基因。将有效重排的VH 4-21基因克隆到pRTM1（一种人类IgM表达载体）中。通过将这些构建体中的每一个与pSVG-Vκ3共转染，我们得以产生表达IgMκ的转染瘤，pSVG-Vκ3是一种Igκ轻链表达载体，其可变区编码Humkv325，这是一个在早期B细胞发育过程中经常表达的保守Vκ基因。我们发现，所有由VH 4-21编码表达IgMκ的转染瘤都会产生与i反应的IgM自身抗体，i是新生儿红细胞上存在的一种线性多聚N-乙酰乳糖胺决定簇，也是CD45表面分子的B细胞限制性同种型。相比之下，一个表达pSVG-Vκ3和pRTM1的转染瘤，其中pRTM1含有从慢性淋巴细胞白血病B细胞群体（命名为WIL）中分离出的重排VH4-59（V71-4）基因，产生的IgMκ抗体没有可检测到的抗i结合活性。然而，发现表达融合到WIL的Ig重链第三互补决定区（CDR3）上的VH 4-21的转染瘤会产生具有抗i活性的抗B细胞自身抗体。这些研究表明，在人类胎儿B细胞发育过程中重排的VH 4-21基因可以编码具有结合特异性的抗B细胞自身抗体，这种特异性不需要体内体细胞选择。
