Yoshida Hitoshi, Tomiyama Yoshiaki, Oritani Kenji, Murayama Yoko, Ishikawa Jun, Kato Hisashi, Miyagawa Ji Jun-ichiro, Honma Nakayuki, Nishiura Tetsuo, Matsuzawa Yuji
Department of Internal Medicine and Molecular Science, Graduate School of Medicine B5, Osaka University, Osaka, Japan.
J Immunol. 2002 Apr 1;168(7):3213-20. doi: 10.4049/jimmunol.168.7.3213.
CD47 modulates a variety of cell functions such as adhesion, spreading, and migration. Using a fusion protein consisting of the extracellular region of Src homology 2 domain bearing protein tyrosine phosphatase substrate-1 (SHPS-1) and the Fc portion of human Ig (SHPS-1-Ig) we investigated the effects of SHPS-1 as a ligand for CD47 on B lymphocytes. Although SHPS-1-Ig binding to human B cell lines was solely mediated via CD47, their binding capacity for soluble and immobilized SHPS-1-Ig varied among cell lines irrespective of the similar expression levels of CD47, suggesting that distinctive affinity/avidity states exist during B cell maturation. Nalm6 cell line and tonsilar B lymphocytes adhered to immobilized SHPS-1-Ig and showed polarization-like morphology. These effects of SHPS-1-Ig were blocked by anti-CD47 mAbs (B6H12 and SE5A5). Wortmannin, a phosphatidylinositol-3 kinase inhibitor, but not pertussis toxin significantly inhibited the polarization induced by the immobilized SHPS-1-Ig. Thus, SHPS-1 acts as an adhesive substrate via CD47 in human B lymphocyte. Immunohistochemical analyses indicated that SHPS-1 is expressed on high endothelial venule as well as macrophages in human tonsils. HUVECs also express SHPS-1 in the absence of any stimuli, and the adhesion of tonsilar B lymphocytes to nonactivated HUVECs was significantly inhibited by SE5A5, indicating that SHPS-1/CD47 interaction is involved in the adhesion. Our findings suggest that SHPS-1/CD47 interaction may contribute to the recruitment of B lymphocytes via endothelial cells under steady state conditions.
CD47调节多种细胞功能，如黏附、铺展和迁移。我们使用一种由含Src同源2结构域的蛋白酪氨酸磷酸酶底物-1（SHPS-1）的胞外区与人Ig的Fc部分组成的融合蛋白（SHPS-1-Ig），研究了作为CD47配体的SHPS-1对B淋巴细胞的影响。尽管SHPS-1-Ig与人B细胞系的结合仅通过CD47介导，但它们对可溶性和固定化SHPS-1-Ig的结合能力在不同细胞系中有所不同，而与CD47的相似表达水平无关，这表明在B细胞成熟过程中存在独特的亲和力/亲合力状态。Nalm6细胞系和扁桃体B淋巴细胞黏附于固定化的SHPS-1-Ig，并呈现极化样形态。SHPS-1-Ig的这些作用被抗CD47单克隆抗体（B6H12和SE5A5）阻断。渥曼青霉素，一种磷脂酰肌醇-3激酶抑制剂，但百日咳毒素不能显著抑制固定化SHPS-1-Ig诱导的极化。因此，SHPS-1通过CD47在人B淋巴细胞中作为黏附底物起作用。免疫组织化学分析表明，SHPS-1在人扁桃体的高内皮微静脉以及巨噬细胞上表达。人脐静脉内皮细胞（HUVECs）在没有任何刺激的情况下也表达SHPS-1，SE5A5显著抑制扁桃体B淋巴细胞对未活化HUVECs的黏附，表明SHPS-1/CD47相互作用参与了黏附过程。我们的研究结果表明，在稳态条件下，SHPS-1/CD47相互作用可能有助于B淋巴细胞通过内皮细胞的募集。
