Murti K G, Brown P S, Kumagai M a, Campana D
Department of Virology and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38101, USA.
Exp Cell Res. 1996 Jul 10;226(1):47-58. doi: 10.1006/excr.1996.0201.
Apoptosis of normal and leukemic immature B-cells in vitro is suppressed when either cell type is grown in direct contact with a feeder layer of bone marrow-derived stromal cells, including fibroblasts, macrophages, endothelial cells, and adipocytes. In this study, our objective was to identify a stromal cell type which is essential for lymphoblast survival and to characterize the molecules involved in lymphoblast adhesion to these cells. In experiments with B-lineage acute lymphoblastic leukemia (ALL) cells (n = 28) and purified CD19(+) cells from normal bone marrow (n = 6) we found that homogeneous populations of bone marrow fibroblasts could sustain survival of normal and leukemic immature B-cells as efficiently as composite bone marrow stromal layers. Electron microscopic studies showed that leukemic lymphoblasts associate with fibroblasts and with the extracellular matrix (ECM) primarily via their specialized cell surface structures. Immunogold labelingsoliduselectron microscopy analysis revealed that the areas of contact between lymphoblasts and fibroblasts contained beta1 integrins (VLA-4 and VLA-5), fibronectin, vascular cell adhesion molecule (VCAM-1), and a cartilage-link protein, CD44. Double immunogold labeling studies disclosed a direct in situ relationship between fibronectin and VLA-4, VLA-5, and CD44. We hypothesize that these molecular interactions either bring lymphoblasts into close physical proximity with other fibroblast-bound or ECM-bound survival factors or provide survival signals themselves.
当正常未成熟B细胞或白血病未成熟B细胞与包括成纤维细胞、巨噬细胞、内皮细胞和脂肪细胞在内的骨髓来源基质细胞饲养层直接接触生长时，其体外凋亡受到抑制。在本研究中，我们的目的是确定一种对淋巴母细胞存活至关重要的基质细胞类型，并表征参与淋巴母细胞与这些细胞粘附的分子。在用B系急性淋巴细胞白血病（ALL）细胞（n = 28）和来自正常骨髓的纯化CD19(+)细胞（n = 6）进行的实验中，我们发现骨髓成纤维细胞的同质群体能够像复合骨髓基质层一样有效地维持正常和白血病未成熟B细胞的存活。电子显微镜研究表明，白血病淋巴母细胞主要通过其特化的细胞表面结构与成纤维细胞和细胞外基质（ECM）相关联。免疫金标记-固相电子显微镜分析显示，淋巴母细胞与成纤维细胞之间的接触区域含有β1整合素（VLA-4和VLA-5）、纤连蛋白、血管细胞粘附分子（VCAM-1）和一种软骨连接蛋白CD44。双重免疫金标记研究揭示了纤连蛋白与VLA-4、VLA-5和CD44之间的直接原位关系。我们推测，这些分子相互作用要么使淋巴母细胞与其他与成纤维细胞结合或与ECM结合的存活因子紧密物理接近，要么自身提供存活信号。
