Allman D, Li J, Hardy R R
Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
J Exp Med. 1999 Feb 15;189(4):735-40. doi: 10.1084/jem.189.4.735.
Lineage commitment in B lymphopoiesis remains poorly understood due to the inability to clearly define newly committed B lineage progenitors and their multipotential descendants. We examined the potential of three recently described progenitor populations in adult mouse bone marrow to differentiate into each hematopoietic lineage. The earliest of these, termed fraction (Fr.) A0, exhibited myeloid, erythroid, and B and T lymphoid progenitor activity and included individual cells with myeloid/B lymphoid potential. In sharp contrast, two later populations, termed Frs. A1 and A2 and characterized by surface B220 expression and transcription of the germline immunoglobulin heavy chain (IgH) locus, lacked progenitor activity for all hematopoietic lineages except B lymphocytes. These observations, together with single cell polymerase chain reaction analysis showing a lack of DHJH rearrangements in each population and experiments showing identical precursor potentials when these populations were derived from recombination activating gene (Rag)-1(-/-) and JH-/- mice, demonstrate that commitment to the B lymphoid lineage occurs before and independently of VHDHJH recombination.
由于无法清晰界定新分化的B淋巴细胞系祖细胞及其多能后代，B淋巴细胞生成过程中的谱系定向仍未得到充分理解。我们研究了成年小鼠骨髓中最近描述的三种祖细胞群体分化为各造血谱系的潜力。其中最早的群体称为A0组分，表现出髓系、红系以及B和T淋巴细胞系祖细胞活性，并且包含具有髓系/B淋巴细胞系潜能的单个细胞。与之形成鲜明对比的是，另外两个较晚的群体，称为A1和A2组分，其特征为表面B220表达以及种系免疫球蛋白重链（IgH）基因座的转录，除了B淋巴细胞外，它们缺乏所有造血谱系的祖细胞活性。这些观察结果，连同单细胞聚合酶链反应分析显示每个群体中缺乏DHJH重排，以及实验表明当这些群体源自重组激活基因（Rag）-1（-/-）和JH-/-小鼠时具有相同的前体潜能，证明了向B淋巴细胞系的定向发生在VHDHJH重组之前且与之无关。
