Salles G, Rodewald H R, Chin B S, Reinherz E L, Shipp M A
Laboratory of Immunobiology, Dana-Farber Cancer Institute, Boston, MA 02115.
Proc Natl Acad Sci U S A. 1993 Aug 15;90(16):7618-22. doi: 10.1073/pnas.90.16.7618.
The common acute lymphoblastic leukemia antigen [(CALLA) CD10, neutral endopeptidase 24.11 (NEP)] is a cell-surface zinc metalloprotease expressed by a subpopulation of early murine B-lymphoid progenitors and by bone marrow stromal cells that support the earliest stages of B lymphopoiesis. In previous in vitro studies in which uncommitted murine hematopoietic progenitors plated on a stromal cell layer differentiate into immature B cells, the inhibition of CD10/NEP increased early lymphoid colony numbers. To further characterize CD10/NEP function during lymphoid ontogeny in vivo, we utilized a Ly5 congenic mouse model in which the lymphoid differentiation of uncommitted hematopoietic progenitors from Ly5.1 donors was followed in sublethally irradiated Ly5.2 recipients treated with a specific long-acting CD10/NEP inhibitor (N-[L-(1-carboxy-2-phenyl)ethyl]-L-phenylalanyl-beta- alanine (SCH32615)). The expression of Ly5.1, B220, and surface IgM (sIgM) was utilized to characterize donor-derived hematopoietic cells (Ly5.1+), B lymphocytes (B220+), and mature B cells (B220+ sIgM+) from the lymphoid organs of recipient animals treated with SCH32615 or vehicle alone. SCH32615-treated animals had higher percentages of Ly5.1+ donor splenocytes than animals treated with vehicle alone (16.9% vs. 10.4%, 63% increase, P = 0.013). Animals treated with the CD10/NEP inhibitor also had relatively more Ly5.1+ splenic B (B220+) cells than vehicle-treated animals (14.4% vs. 8.2%, 75% increase, P = 0.018). To more specifically characterize the effects of CD10/NEP inhibition on B-cell differentiation, Ly5.1+ splenocytes from animals treated with SCH32615 or vehicle alone were analyzed for coexpression of B220 and sIgM. Animals treated with the CD10/NEP inhibitor had a significantly higher percentage of mature donor B cells (Ly5.1+ B220+ sIgM+, 10.2% vs. 5.2%, 90% increase, P = 0.006) and a more modest relative increase in immature donor B cells (Ly5.1+ B220+ sIgM-, 4.7% vs. 3.4%, 38% increase, P = not significant). Taken together, these results suggest that CD10/NEP inhibition promotes the reconstitution and maturation of splenic B cells. Therefore, CD10/NEP may function to regulate B-cell ontogeny in vivo by hydrolyzing a peptide substrate that stimulates B-cell proliferation and/or differentiation.
常见急性淋巴细胞白血病抗原[（CALLA）CD10，中性内肽酶24.11（NEP）]是一种细胞表面锌金属蛋白酶，由早期小鼠B淋巴细胞祖细胞亚群以及支持B淋巴细胞生成最早阶段的骨髓基质细胞表达。在之前的体外研究中，未定向的小鼠造血祖细胞接种在基质细胞层上分化为未成熟B细胞，抑制CD10/NEP可增加早期淋巴细胞集落数量。为了进一步在体内淋巴发育过程中表征CD10/NEP的功能，我们利用了Ly5同基因小鼠模型，在经亚致死剂量照射并用特异性长效CD10/NEP抑制剂（N-[L-（1-羧基-2-苯基）乙基]-L-苯丙氨酰-β-丙氨酸（SCH32615））处理的Ly5.2受体中追踪来自Ly5.1供体的未定向造血祖细胞的淋巴分化。利用Ly5.1、B220和表面IgM（sIgM）的表达来表征用SCH32615或单独载体处理的受体动物淋巴器官中供体来源的造血细胞（Ly5.1+）、B淋巴细胞（B220+）和成熟B细胞（B220+sIgM+）。与单独用载体处理的动物相比，用SCH32615处理的动物中Ly5.1+供体脾细胞的百分比更高（16.9%对10.4%，增加63%，P=0.013）。用CD10/NEP抑制剂处理的动物中Ly5.1+脾B（B220+）细胞也比用载体处理的动物相对更多（14.4%对8.2%，增加75%，P=0.018）。为了更具体地表征CD10/NEP抑制对B细胞分化的影响，分析了用SCH32615或单独载体处理的动物的Ly5.1+脾细胞中B220和sIgM的共表达情况。用CD10/NEP抑制剂处理的动物中成熟供体B细胞（Ly5.1+B220+sIgM+）的百分比显著更高（10.2%对5.2%，增加90%，P=0.006），而未成熟供体B细胞（Ly5.1+B220+sIgM-）的相对增加幅度较小（4.7%对3.4%，增加38%，P无显著性）。综上所述，这些结果表明CD10/NEP抑制促进脾B细胞的重建和成熟。因此，CD10/NEP可能通过水解刺激B细胞增殖和/或分化的肽底物来在体内调节B细胞发育。
