67 KD LAMININ BINDING PROTEIN ON HUMAN T LYMPHOCYTES

T细胞与层粘连蛋白（基底膜的主要糖蛋白）的相互作用对炎症反应很重要。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理解。对活化T细胞中表达的基因的搜索显示，非整合素，67 kD层粘连蛋白（p67 LBP）在活化外周血T细胞的一个亚群（10- 15%）表面表达。使用抗p67 LBP单抗MLuC5， FACS检测表面p67 LBP表达，在PDB和离子霉素激活T细胞后6小时内，激活后24小时达到峰值，持续7-10天。表达p67 LBP的T细胞亚群是成熟的、记忆细胞表型（100% CD45 RO+/CD45 RA-）的单阳性细胞（85% CD4+/8-, 15% CD4-/8+）。p67 LBP+ T细胞也表达整合素α 6链（CD49f），已知其与肿瘤细胞上的p67 LBP相关。此外，p67 LBP+ T细胞表达整合素beta1，该整合素在层粘连蛋白特异性整合素受体VLA-6 （alpha6beta1）中与alpha6结合。外源cDNA编码37 kD LBP前体（p37 LBPP）的表达使p67 LBP表面在p67 LBP阴性Jurkat T细胞系上表达（B2.7）。p67 LBP的表达诱导B2.7转染物粘附在层粘连蛋白上，但层粘连蛋白的强烈结合依赖于高水平的VLA-6的共表达。综上所述，这些数据表明p67 LBP是激活诱导的记忆T细胞表面结构，它与VLA-6一起介导细胞对层粘连蛋白的粘附。我们建议在正常人T细胞和Jurkat T细胞系上研究p67 LBP，以解决以下具体目标：(1)什么刺激诱导p67 LBP在正常T细胞上的表达？(2) p67 LBP的结构是什么？(3) p67 LBP和整合素alpha6对淋巴细胞层粘连蛋白特异性粘附的贡献是什么？(4) p67 LBP和alpha6对层粘连蛋白介导的板足形成、运动和跨内皮迁移的贡献是什么？

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?