Funk P E, Stephan R P, Witte P L
Department of Cell Biology, Loyola University Medical Center, Maywood, IL 60153, USA.
Blood. 1995 Oct 1;86(7):2661-71.
In vitro studies have defined an essential role for stromal cells in supporting B-cell development, including production of lymphopoietic cytokines. It has been suggested that stromal cells are equivalent to adventitial reticular cells in the marrow; however, evidence of reticular cells producing cytokines has been difficult to obtain. Staining of bone marrow (BM) sections with antibodies to interleukin-7 (IL-7) showed a reticular pattern, mimicking that obtained using antibodies to vascular cell adhesion molecule 1 (VCAM-1), a molecule present on both stromal cells in vitro and reticular cells. To more closely examine cytokine production within normal marrow, an immunomagnetic separation scheme was devised to directly enrich VCAM-1+ stromal cells. Twenty to thirty percent of cells isolated in the VCAM-1+ fraction shared characteristics with stromal cells from long term BM cultures, including cellular morphology and expression of alkaline phosphatase and alpha actin. These were termed "reticular stromal" cells. Immunohistochemical staining showed that virtually all of the latter cells possessed cytoplasmic IL-7 protein, and about half expressed stem cell factor. In contrast with cultured stromal cells, very few had detectable macrophage-colony-stimulating factor. These data constitute the first report of cytokine expression by marrow reticular cells in vivo. The implications of this data with respect to the existence of stromal cell subsets and their regulation of lymphopoiesis is discussed.
体外研究已经明确了基质细胞在支持B细胞发育过程中的重要作用，包括产生淋巴细胞生成细胞因子。有人提出基质细胞等同于骨髓中的外膜网状细胞；然而，很难获得网状细胞产生细胞因子的证据。用白细胞介素-7（IL-7）抗体对骨髓（BM）切片进行染色显示出一种网状模式，类似于使用血管细胞黏附分子1（VCAM-1）抗体所获得的模式，VCAM-1是一种在体外基质细胞和网状细胞上均存在的分子。为了更仔细地研究正常骨髓内的细胞因子产生情况，设计了一种免疫磁珠分离方案，以直接富集VCAM-1+基质细胞。从VCAM-1+组分中分离出的细胞有20%至30%与长期骨髓培养中的基质细胞具有共同特征，包括细胞形态以及碱性磷酸酶和α肌动蛋白的表达。这些细胞被称为“网状基质”细胞。免疫组织化学染色显示，实际上所有这些细胞都含有细胞质IL-7蛋白，约一半表达干细胞因子。与培养的基质细胞相比，很少有细胞能检测到巨噬细胞集落刺激因子。这些数据构成了体内骨髓网状细胞细胞因子表达的首次报道。讨论了这些数据对于基质细胞亚群的存在及其对淋巴细胞生成的调节的意义。
