Deguchi T, Komada Y, Sugiyama K, Zhang X L, Azuma E, Yamamoto H, Sakurai M
Department of Pediatrics, Mie University School of Medicine, Japan.
Exp Hematol. 1999 Mar;27(3):542-52. doi: 10.1016/s0301-472x(98)00047-2.
We investigated the expression of CD44 molecule on CD34+ hematopoietic progenitor cells. Significantly lower expression of CD44 was observed on bone marrow (BM) CD34+ cells compared with circulating CD34+ cells in cord blood and peripheral blood. Using fluorescence-activated cell sorting, human CD34+ BM cells were fractionated into CD44+ and CD44- populations. Immunofluorescence analysis revealed that the majority of CD34+CD44- cells expressed B-lymphocyte-associated CD10 and CD19 antigens, whereas only a part of CD34+CD44+ cells were positive for CD19. Myeloid and erythroid progenitor cells were found predominantly in CD34+ CD44+ cell fractions. In short-term suspension cultures, cell proliferation and G1-->S transition in the cell cycle were enhanced in CD34+CD44+ cells. In contrast, a large part of CD34+CD44- cells underwent apoptotic cell death. Although co-culture with BM stromal cells could partially prevent CD34+CD44- cells from undergoing apoptosis, significant increase of apoptotic cells was consistently observed. Furthermore, CD34+CD44- cells plated on BM stromal cells could differentiate into CD34-CD44-CD10-CD19+ cells. These findings suggest that CD34+CD44- cells expressing CD19 would represent unique B-lymphocyte-committed precursors in BM, which might undergo apoptotic cell death in the early steps of B-cell differentiation.
我们研究了CD44分子在CD34+造血祖细胞上的表达。与脐血和外周血中的循环CD34+细胞相比，骨髓（BM）CD34+细胞上CD44的表达明显较低。利用荧光激活细胞分选技术，将人CD34+ BM细胞分为CD44+和CD44-群体。免疫荧光分析显示，大多数CD34+CD44-细胞表达B淋巴细胞相关的CD10和CD19抗原，而只有一部分CD34+CD44+细胞CD19呈阳性。髓系和红系祖细胞主要存在于CD34+ CD44+细胞组分中。在短期悬浮培养中，CD34+CD44+细胞的细胞增殖和细胞周期中的G1期向S期转变增强。相反，大部分CD34+CD44-细胞发生凋亡性细胞死亡。虽然与BM基质细胞共培养可部分阻止CD34+CD44-细胞发生凋亡，但凋亡细胞仍持续显著增加。此外，接种在BM基质细胞上的CD34+CD44-细胞可分化为CD34-CD44-CD10-CD19+细胞。这些发现表明，表达CD19的CD34+CD44-细胞可能代表BM中独特的B淋巴细胞定向前体细胞，它们可能在B细胞分化的早期阶段发生凋亡性细胞死亡。
