Sadahira Y, Yoshino T, Monobe Y
Department of Pathology, Kawasaki Medical School, Kurashiki, Japan.
J Exp Med. 1995 Jan 1;181(1):411-5. doi: 10.1084/jem.181.1.411.
Erythroblastic islands are anatomical units consisting of a central macrophage surrounded by erythroblasts. We studied the adhesion molecules involved in the formation of these structures. Central macrophages of erythroblastic islands isolated from the spleens of phlebotomized mice were clearly stained for vascular cell adhesion molecule 1 (VCAM-1). The surrounding erythroblasts of the erythroblastic islands strongly expressed the alpha 4 integrin of very late activation antigen 4 (VLA-4: alpha 4 beta 1 integrin), the counter receptor of VCAM-1, whereas most reticulocytes and erythrocytes did not. Both monoclonal antibodies (mAbs) against alpha 4 integrin and VCAM-1 disrupted the erythroblastic islands cultured in the presence of erythropoietin. Moreover, adhesion of splenic erythroblasts to tumor necrosis factor alpha-stimulated mouse splenic endothelial cells, which showed high expression of VCAM-1 but not intercellular adhesion molecule 1, was inhibited by the anti-VCAM-1 and anti-alpha 4 mAbs. These findings suggest that VLA-4-VCAM-1 interaction plays a crucial role in the formation of erythroblastic islands.
红细胞岛是由一个中央巨噬细胞及其周围的成红细胞组成的解剖学单位。我们研究了参与这些结构形成的黏附分子。从放血小鼠脾脏中分离出的红细胞岛的中央巨噬细胞，血管细胞黏附分子1（VCAM-1）染色清晰。红细胞岛周围的成红细胞强烈表达晚期活化抗原4（VLA-4：α4β1整合素）的α4整合素，它是VCAM-1的反受体，而大多数网织红细胞和红细胞则不表达。抗α4整合素和VCAM-1的单克隆抗体（mAb）均破坏了在促红细胞生成素存在下培养的红细胞岛。此外，抗VCAM-1和抗α4 mAb抑制了脾成红细胞与肿瘤坏死因子α刺激的小鼠脾内皮细胞的黏附，后者高表达VCAM-1但不表达细胞间黏附分子1。这些发现表明VLA-4-VCAM-1相互作用在红细胞岛的形成中起关键作用。
