Sanz Eva, Alvarez-Mon Melchor, Martínez-A Carlos, de la Hera Antonio
Laboratory of Immunology and Oncology, Consejo Superior de Investigaciones Cientificas-Alcalá University Research Associated Unit, Madrid, Spain.
Blood. 2003 May 1;101(9):3424-30. doi: 10.1182/blood-2002-07-2244. Epub 2002 Nov 21.
Circulating CD34(+) cells are used in reparative medicine as a stem cell source, but they contain cells already committed to different lineages. Many think that B-cell progenitors (BCPs) are confined to bone marrow (BM) niches until they differentiate into B cells and that they do not circulate in blood. The prevailing convention is that BCP transit a CD34(+)CD19(-)10(+) early-B-->CD34(+)CD19(+)CD10(+) B-cell progenitor (pro-B)-->CD34(-)CD19(+)CD10(+) B-cell precursor (pre-B) differentiation pathway within BM. However, populations of CD34(+)CD10(+) and CD34(+)CD19(+) cells circulate in adult peripheral blood and neonatal umbilical cord blood (CB) that are operationally taken as BCPs on the basis of their phenotypes, although they have not been submitted to a systematic characterization of their gene expression profiles. Here, conventional CD34(+)CD19(+)CD10(+) and novel CD34(+)CD19(+)CD10(-) BCP populations are characterized in CB by single-cell sorting and multiplex analyses of gene expression patterns. Circulating BCP are Pax-5(+) cells that span the early-B, pro-B, and pre-B developmental stages, defined by the profiles of rearranged V-D-J(H), CD79, VpreB, recombination activating gene (RAG), and terminal deoxynucleotidyl transferase (TdT) expression. Contrary to the expectation, circulating CD34(+)CD19(-)CD10(+) cells are essentially devoid of Pax-5(+) BCP. Interestingly, the novel CD34(+)CD19(+)CD10(-) BCP appears to be the normal counterpart of circulating preleukemic BCPs that undergo chromosomal translocations in utero months or years before their promotion into infant acute lymphoblastic B-cell leukemia after secondary postnatal mutations. The results underscore the power of single-cell analyses to characterize the gene expression profiles in a minor population of rare cells, which has broad implications in biomedicine.
循环中的CD34(+)细胞作为干细胞来源被用于再生医学，但它们包含已定向分化为不同谱系的细胞。许多人认为B细胞祖细胞（BCP）在分化为B细胞之前局限于骨髓龛中，且不会在血液中循环。目前的普遍观点是，BCP在骨髓内通过CD34(+)CD19(-)10(+)早期B细胞-->CD34(+)CD19(+)CD10(+) B细胞祖细胞（前B细胞）-->CD34(-)CD19(+)CD10(+) B细胞前体（前B细胞）的分化途径。然而，CD34(+)CD10(+)和CD34(+)CD19(+)细胞群体存在于成人外周血和新生儿脐带血（CB）中，基于其表型在操作上被视为BCP，尽管它们尚未接受基因表达谱的系统表征。在此，通过单细胞分选和基因表达模式的多重分析对脐带血中的传统CD34(+)CD19(+)CD10(+)和新型CD34(+)CD19(+)CD10(-) BCP群体进行了表征。循环中的BCP是Pax-5(+)细胞，跨越早期B细胞、前B细胞和前B细胞发育阶段，由重排的V-D-J(H)、CD79、VpreB、重组激活基因（RAG）和末端脱氧核苷酸转移酶（TdT）表达谱定义。与预期相反，循环中的CD34(+)CD19(-)CD10(+)细胞基本上没有Pax-5(+) BCP。有趣的是，新型CD34(+)CD19(+)CD10(-) BCP似乎是循环中白血病前期BCP的正常对应物，这些BCP在子宫内经历染色体易位，数月或数年后在出生后二次突变后发展为婴儿急性淋巴细胞B细胞白血病。这些结果强调了单细胞分析在表征稀有细胞少数群体基因表达谱方面的能力，这在生物医学中具有广泛的意义。
