deCastro C M, Denning S M, Langdon S, Vandenbark G R, Kurtzberg J, Scearce R, Haynes B F, Kaufman R E
Department of Medicine, Duke University Medical Center, Durham, NC 27710.
Exp Hematol. 1994 Sep;22(10):1025-33.
The c-kit receptor is a tyrosine-kinase transmembrane receptor first identified as an oncogene in the HZ4-feline leukemia virus and later found to be important in hematopoiesis in mice. The ligand for this receptor (Steel factor) can stimulate hematopoiesis both in vitro and in vivo. To study the pattern of c-kit receptor expression in normal human hematopoietic progenitor cells, we prepared a monoclonal antibody (9B9) against human c-kit receptor by using a synthetic peptide (amino acids 476-501) from the extracellular domain of c-kit receptor to immunize Balb/c mice. Monoclonal antibody 9B9 bound to recombinant c-kit protein, the erythroleukemic line HEL, the megakaryocytic line MEG-01, and the murine mast cell line P815. Monoclonal antibody 9B9 also bound to the surface of the CD7+CD3-CD4-CD8- T cell lymphoid cell lines DU.528 and HSB2T, and also to 1 to 4% of normal bone-marrow cells. The majority (67 +/- 6%) of CD34+ bone-marrow progenitor cells coexpressed c-kit receptor. Flow-cytometry analysis of immature CD3-CD4-CD8- (triple-negative) thymocytes indicated 30 +/- 9.5% expressed the c-kit receptor, and thymidine incorporation assay revealed that the receptor is functional. Indirect fluorescent microscopy of human thymic tissue, using a monoclonal antibody against Steel factor, revealed its presence on scattered mononuclear cells within the intralobular septae and the subcapsular cortex, which are regions where the triple-negative thymocytes are also localized. These data provide evidence that the c-kit receptor is present on human hematopoietic bone marrow and intrathymic T cell progenitor cells, and that it likely plays a role in early T cell lymphopoiesis.
c-kit受体是一种酪氨酸激酶跨膜受体，最初在HZ4-猫白血病病毒中被鉴定为癌基因，后来发现它在小鼠造血过程中起重要作用。该受体的配体（Steel因子）可在体外和体内刺激造血。为了研究c-kit受体在正常人造血祖细胞中的表达模式，我们使用来自c-kit受体胞外结构域的合成肽（氨基酸476-501）免疫Balb/c小鼠，制备了一种抗人c-kit受体的单克隆抗体（9B9）。单克隆抗体9B9与重组c-kit蛋白、红白血病细胞系HEL、巨核细胞系MEG-01以及小鼠肥大细胞系P815结合。单克隆抗体9B9也与CD7+CD3-CD4-CD8-T细胞淋巴瘤细胞系DU.528和HSB2T的表面结合，还与1%至4%的正常骨髓细胞结合。大多数（67±6%）CD34+骨髓祖细胞共表达c-kit受体。对未成熟的CD3-CD4-CD8-（三阴性）胸腺细胞进行流式细胞术分析表明，30±9.5%的细胞表达c-kit受体，胸腺嘧啶掺入试验表明该受体具有功能。使用抗Steel因子的单克隆抗体对人胸腺组织进行间接荧光显微镜检查，发现其存在于小叶间隔和被膜下皮质内的散在单核细胞上，而这些区域也是三阴性胸腺细胞所在的部位。这些数据证明c-kit受体存在于人类造血骨髓和胸腺内T细胞祖细胞上，并且它可能在早期T细胞淋巴细胞生成中发挥作用。
