67 KD LAMININ BINDING PROTEIN ON HUMAN T LYMPHOCYTES

T细胞与基底膜的主要糖蛋白--层粘连蛋白的相互作用在炎症反应中起重要作用。然而，淋巴细胞表面受体与层粘连蛋白的相互作用才刚刚开始被了解。对活化T细胞中表达的基因的搜索发现，非整合素67kD的层粘连蛋白结合蛋白(P67LBP)表达在活化的T细胞亚群(10%-15%)的表面。使用抗p67 LBP单抗MLuC5的流式细胞仪检测到p67 LBP的表达，在用PDB和离子霉素激活T细胞的6h内，在激活后24 h达到高峰，并持续7-10天。表达p67 LBP的T细胞亚群是成熟的单一阳性细胞(85%的CD4+/8-，15%的CD4-/8+)，具有记忆细胞表型(100%CD45RO+/CD45RA-)。P67 LBP+T细胞还表达整合素α6链(CD49f)，该链与肿瘤细胞上的p67 LBP相关。此外，p67 LBP+T细胞表达整合素Beta1，它与层粘连蛋白特异性整合素受体VLA-6(Alpha6beta1)中的Alpha6相关。编码37 kD LBP前体(P37 LBPP)的外源cDNA的表达使p67 LBP阴性的Jurkat T细胞株(B2.7)表面表达p67 LBP。P67 LBP的表达诱导B2.7转染体与层粘连蛋白的粘附性，但层粘连蛋白的亲和性依赖于高水平VLA-6的共表达。综上所述，这些数据表明，p67 LBP是记忆T细胞上一种激活诱导的表面结构，与VLA-6一起，介导细胞对层粘连蛋白的黏附。我们建议研究p67 LBP在正常人T细胞和Jurkat T细胞系上的表达，以达到以下目的：(1)什么刺激诱导正常T细胞上p67 LBP的表达？(2)p67 LBP的结构是什么？(3)p67 LBP和整合素α6对淋巴细胞层粘连蛋白特异性黏附有什么贡献？以及(4)p67 LBP和Alpha6对层粘连蛋白介导层椭圆形的形成、运动和跨内皮细胞迁移有何贡献？

T cell interactions with laminin, the major glycoprotein of basement membranes, are important to the inflammatory response. However, the interactions of lymphocyte surface receptors with laminin are only beginning to be understood. A search for genes expressed in activated T cells revealed that the non-integrin, 67 kD laminin binding protein (p67 LBP) is expressed on the surface of a subset (10-15 percent) of activated peripheral blood T cells. Surface p67 LBP expression is detectable by FACS using the anti-p67 LBP mAb, MLuC5, within 6 h of T cell activation with PDB and ionomycin, peaks 24 h post-activation, and persists for 7-10 days. The subset of T cells expressing p67 LBP are mature, single-positive cells (85 percent CD4+/8-, 15 percent CD4-/8+) of memory cell phenotype (100 percent CD45 RO+/CD45 RA-). The p67 LBP+ T cells also express the integrin alpha6 chain (CD49f), which is known to associate with p67 LBP on tumor cells. In addition, the p67 LBP+ T cells express the integrin beta1, which associates with alpha6 in the laminin-specific integrin receptor VLA-6 (alpha6beta1). Expression of an exogenous cDNA encoding the 37 kD LBP precursor (p37 LBPP) confers p67 LBP surface expression on a p67 LBP-negative Jurkat T cell line (B2.7). Expression of p67 LBP induces B2.7 transfectants to adhere to laminin, but avid laminin binding depends on co-expression of high level VLA-6. Taken together, these data indicate that p67 LBP is an activation-induced surface structure on memory T cells that, together with VLA-6, mediates cellular adherence to laminin. We propose to study p67 LBP on normal human T cells and on the Jurkat T cell line in order to address the following specific aims: (1) What stimuli induce the expression of p67 LBP on normal T cells? (2) What is the structure of p67 LBP? (3) What are the contributions of p67 LBP and the integrin alpha6 to lymphocyte laminin-specific adherence? and (4) What are the contributions of p67 LBP and alpha6 to laminin-mediated lamellipod formation, locomotion, and transendothelial migration?