Hill B, Rozler E, Travis M, Chen S, Zannetino A, Simmons P, Galy A, Chen B, Hoffman R
SyStemix, Palo Alto, CA 94304, USA.
Exp Hematol. 1996 Jul;24(8):936-43.
To further define the hierarchy of human hematopoietic progenitor cells, we have attempted to identify antibodies to cell-surface molecules expressed on CD34+ progenitor cell subsets. Herein we describe the utility of a new monoclonal antibody, HCC-1, which binds to a novel epitope of CD59 differentially expressed among CD34+ progenitor cells. HCC-1 subdivides the adult marrow CD34+ population into HCC-1high and HCC-1low/- fractions of approximately equal size. Cobblestone area-forming cells (CAFC) in long-term bone marrow culture were enriched 10-30-fold in CD34+HCC-1high cells compared with CD34+HCC1-low/- cells and two-fold compared with CD34+ cells. When injected into fetal human bone fragments implanted in SCID mice, the CD34+HCC-1high population showed potent engrafting activity leading to the production of myeloid, lymphoid, and erythroid elements, as well as the retention of progenitor cell phenotype. These studies demonstrate that the CD34+HCC-1high population contains primitive pluripotent hematopoietic stem cells. No hematopoietic engrafting activity was detected in the CD34+HCC-1low/- population. Consistent with this finding, simultaneous five-color flow cytometric analysis revealed that HCC-1high cells include virtually all CD34+Thy-1+Lin- cells, a cell population previously characterized as highly enriched for primitive pluripotent hematopoietic stem cells. The ability of CD34+ cells divided into subsets by HCC-1 to produce T cells was assessed by transplantation of sorted cells into human fetal thymus implanted into SCID mice. A higher frequency of thymus-engrafting activity was observed in the CD34+HCC-1high than in the CD34+HCC-1low/- population. Consistent with the limited ability to engraft in the SCID-hu thymus model, the CD34+HCC-1low/- population was shown to contain a low frequency of CD34+CD10+ lymphoid progenitor cells. We conclude that the HCC-1 epitope is expressed at high levels on a subset of CD34+ cells that contain virtually all primitive pluripotent hematopoietic stem cells and that the population of CD59 molecules expressed on CD34+ cells is not homogeneous.
为了进一步明确人类造血祖细胞的层次结构，我们试图鉴定针对CD34 +祖细胞亚群上表达的细胞表面分子的抗体。在此，我们描述了一种新的单克隆抗体HCC - 1的效用，它与CD59的一个新表位结合，该表位在CD34 +祖细胞中差异表达。HCC - 1将成人骨髓CD34 +群体细分为大小大致相等的HCC - 1高表达和HCC - 1低表达/阴性部分。与CD34 + HCC1低表达/阴性细胞相比，长期骨髓培养中的鹅卵石区域形成细胞（CAFC）在CD34 + HCC - 1高表达细胞中富集了10 - 30倍，与CD34 +细胞相比富集了两倍。当注射到植入SCID小鼠体内的人胎儿骨碎片中时，CD34 + HCC - 1高表达群体显示出强大的植入活性，导致髓系、淋巴系和红系细胞的产生，以及祖细胞表型的保留。这些研究表明，CD34 + HCC - 1高表达群体包含原始多能造血干细胞。在CD34 + HCC - 1低表达/阴性群体中未检测到造血植入活性。与此发现一致，同步五色流式细胞术分析显示，HCC - 1高表达细胞几乎包括所有CD34 + Thy - 1 + Lin -细胞，该细胞群体先前被表征为高度富集原始多能造血干细胞。通过将分选的细胞移植到植入SCID小鼠体内的人胎儿胸腺中，评估了被HCC - 1分为亚群的CD34 +细胞产生T细胞的能力。在CD34 + HCC - 1高表达群体中观察到的胸腺植入活性频率高于CD34 + HCC - 1低表达/阴性群体。与在SCID - hu胸腺模型中有限的植入能力一致，CD34 + HCC - 1低表达/阴性群体被证明含有低频率的CD34 + CD10 +淋巴祖细胞。我们得出结论，HCC - 1表位在包含几乎所有原始多能造血干细胞的CD34 +细胞亚群上高水平表达，并且CD34 +细胞上表达的CD59分子群体不是同质的。
