Akashi K, Kondo M, Weissman I L
Department of Pathology, Standford University School of Medicine 94305, USA.
Immunol Rev. 1998 Oct;165:13-28. doi: 10.1111/j.1600-065x.1998.tb01226.x.
All lymphocytes are derived from hematopoietic stem cells (HSC). The interleukin-7 receptor (IL-7R) transduces non-redundant signals for both T and B-cell development from HSC. The upregulation of the IL-7R occurs at the stage of the clonogenic common lymphoid progenitor, a recently identified population that can give rise to all lymphoid lineages (T, B and natural killer cells) at a single cell level. The IL-7R plays a critical role in the rearrangement of immunoglobulin heavy chain genes required for B-cell development. IL-7R expression is critically regulated in developing thymocytes; thymocytes that fail the positive selection process downregulate the IL-7R, but those undergoing positive selection upregulate or maintain IL-7R expression. Recent data indicate that IL-7 signaling enhances the survival of developing thymocytes and mature T cells, presumably by its upregulating Bcl-2. Detailed analysis of the signaling cascades activated by the IL-7R may help to reveal the differential roles of IL-7 signaling in T and B-cell development.
所有淋巴细胞均来源于造血干细胞（HSC）。白细胞介素-7受体（IL-7R）转导来自HSC的T细胞和B细胞发育所需的非冗余信号。IL-7R的上调发生在克隆性共同淋巴祖细胞阶段，这是一个最近发现的群体，在单细胞水平上可以产生所有淋巴谱系（T细胞、B细胞和自然杀伤细胞）。IL-7R在B细胞发育所需的免疫球蛋白重链基因重排中起关键作用。IL-7R的表达在发育中的胸腺细胞中受到严格调控；未能通过阳性选择过程的胸腺细胞下调IL-7R，但经历阳性选择的胸腺细胞上调或维持IL-7R表达。最近的数据表明，IL-7信号增强了发育中的胸腺细胞和成熟T细胞的存活，可能是通过上调Bcl-2来实现的。对IL-7R激活的信号级联的详细分析可能有助于揭示IL-7信号在T细胞和B细胞发育中的不同作用。
