Akashi K, Traver D, Kondo M, Weissman I L
Department of Pathology, Stanford University School of Medicine, California 94305, USA.
Int J Hematol. 1999 Jun;69(4):217-26.
Mechanisms and pathways for commitment to the lymphoid lineage from hematopoietic stem cells (HSC) remain controversial. The interleukin-7 receptor (IL-7R) transduces nonredundant signals for both T- and B-cell development. Recently, we identified a clonogenic common lymphoid progenitor population in mouse bone marrow that can give rise to T, B, and natural killer (NK) cells, but lacks myeloid differentiation capacity. These cells are not self-renewing stem cells, but progenitors that have a limited life span. HSC do not express IL-7R, and the upregulation of the IL-7R occurs at the stage of common lymphoid progenitors. The IL-7R mediates nonredundant signals to reinforce the survival of developing T cells, and to promote rearrangement of immunoglobulin heavy chain genes in B-cell progenitors. Thus, common lymphoid progenitors exist in early hematopoiesis, and expression of the IL-7R is a critical step in the initiation of lymphoid development from HSC.
造血干细胞（HSC）向淋巴谱系定向分化的机制和途径仍存在争议。白细胞介素-7受体（IL-7R）转导对T细胞和B细胞发育均不可或缺的信号。最近，我们在小鼠骨髓中鉴定出一种克隆性共同淋巴祖细胞群体，它可产生T细胞、B细胞和自然杀伤（NK）细胞，但缺乏髓系分化能力。这些细胞不是自我更新的干细胞，而是寿命有限的祖细胞。造血干细胞不表达IL-7R，IL-7R的上调发生在共同淋巴祖细胞阶段。IL-7R介导不可或缺的信号，以增强发育中T细胞的存活，并促进B细胞祖细胞中免疫球蛋白重链基因的重排。因此，共同淋巴祖细胞存在于早期造血过程中，IL-7R的表达是造血干细胞启动淋巴发育的关键步骤。
