Bertrand F E, Billips L G, Gartland G L, Kubagawa H, Schroeder H W
Division of Developmental and Clinical Immunology, Department of Microbiology, University of Alabama at Birmingham, AL 35294, USA.
J Immunol. 1996 Jun 1;156(11):4240-4.
In mice and chickens, J chain appears to be expressed only in activated B cells and plasma cells. In humans, studies based mainly on transformed cells suggest that J chain expression may initiate during earlier stages in B lineage differentiation. In the present study, we isolated a series of hematopoietic subpopulations from human fetal and adult tissues by immunofluorescence cell sorting and examined each subpopulation for J chain expression by reverse transcriptase-PCR. In fetal and adult bone marrow, J chain transcripts were detected at all stages of B lineage differentiation, including the progenitor (CD34+/CD19-) and pro-B (CD34+/CD19+) cell subpopulations. J chain mRNA was also detected during fetal thymocyte development: double negative (CD4-/CD8-) through single positive (CD4+ or CD8+) cell subpopulations. The J chain message was not detected in peripheral CD3+ T cells, CD14+ monocytes, and CD56+ NK cells from either fetal or adult samples. The nucleotide sequence of J chain PCR products from CD34+/CD19- bone marrow progenitors and CD4+/CD8- thymocytes proved identical to the previously reported sequence of functionally spliced J chain mRNA. These results suggest that the J chain gene is transcriptionally active during early stages of both B cell and T cell differentiation, before the expression of their respective Ag receptors.
在小鼠和鸡中，J链似乎仅在活化的B细胞和浆细胞中表达。在人类中，主要基于转化细胞的研究表明，J链表达可能在B细胞系分化的早期阶段就开始了。在本研究中，我们通过免疫荧光细胞分选从人胎儿和成人组织中分离出一系列造血亚群，并通过逆转录聚合酶链反应检测每个亚群的J链表达。在胎儿和成人骨髓中，在B细胞系分化的所有阶段都检测到了J链转录本，包括祖细胞（CD34+/CD19-）和前B细胞（CD34+/CD19+）亚群。在胎儿胸腺细胞发育过程中也检测到了J链mRNA：从双阴性（CD4-/CD8-）到单阳性（CD4+或CD8+）细胞亚群。在胎儿或成人样本的外周CD3+T细胞、CD14+单核细胞和CD56+NK细胞中未检测到J链信息。来自CD34+/CD19-骨髓祖细胞和CD4+/CD8-胸腺细胞的J链PCR产物的核苷酸序列与先前报道的功能剪接的J链mRNA序列相同。这些结果表明，在B细胞和T细胞分化的早期阶段，在它们各自的抗原受体表达之前，J链基因具有转录活性。
