Kannan K, Stewart R M, Bounds W, Carlsson S R, Fukuda M, Betzing K W, Holcombe R F
Department of Medicine and Center for Excellence in Cancer Research, Louisana State University Medical Center, Shreveport, Louisiana 71130-3932, USA.
Cell Immunol. 1996 Jul 10;171(1):10-9. doi: 10.1006/cimm.1996.0167.
Lysosome-associated membrane proteins (LAMPs) are transmembrane lysosomal glycoproteins which are detectable at the cell surface of lymphocytes in patients with scleroderma and systemic lupus erythematosus. While these proteins have been shown to mediate adhesion of tumor cells to vascular endothelial selectins, the function of LAMPs expressed at the cell surface of peripheral blood lymphocytes has not been previously examined. In the present study, the role of lamp2 (CD107b) in lymphocyte adhesion to vascular endothelium and the factors which influence in vitro cell surface expression of both lamp1 (CD107a) and lamp2 (CD107b) are examined. Freshly isolated PBMCs and unstimulated PBMCs in the culture had low levels of cell surface lamp1 and lamp2 expression which were significantly increased following PHA stimulation (P < 0.0001). A dose-dependent response to PHA and the effect of varying concentrations of serum were defined. Kinetic analysis revealed that the majority of the increase in both lamp1 and lamp2 occurred within the first 2 hr of incubation and that a subset of PBMCs maintained expression for at least 96 hr. Incubation of cells with colchicine and cycloheximide modified the cell surface expression of these proteins. Interleukins 2, 4, 6, and 8 had only a modest effect on the degree of cell surface lamp1 and lamp2 expression, though they did significantly affect the distribution of expression among different subtypes of lymphoid cells. Under the conditions utilized in this study, cell surface LAMP expression was confined primarily to CD56+ cells and to CD3+ cells. Functional analysis utilizing a fluorescence-based adhesion assay revealed that cell surface lamp2 mediates adhesion of PBMCs to vascular endothelium, possibly by interacting with endothelial selectins. LAMPs likely contribute to the migration of activated leukocytes to sites of inflammation in vivo.
溶酶体相关膜蛋白（LAMPs）是跨膜溶酶体糖蛋白，在硬皮病和系统性红斑狼疮患者的淋巴细胞细胞表面可检测到。虽然这些蛋白已被证明可介导肿瘤细胞与血管内皮选择素的黏附，但外周血淋巴细胞细胞表面表达的LAMPs的功能此前尚未得到研究。在本研究中，检测了lamp2（CD107b）在淋巴细胞与血管内皮黏附中的作用以及影响lamp1（CD107a）和lamp2（CD107b）体外细胞表面表达的因素。新鲜分离的外周血单核细胞（PBMCs）和培养中未刺激的PBMCs细胞表面lamp1和lamp2表达水平较低，在PHA刺激后显著增加（P < 0.0001）。确定了对PHA的剂量依赖性反应以及不同浓度血清的影响。动力学分析显示，lamp1和lamp2的大部分增加发生在孵育的前2小时内，并且一部分PBMCs至少维持表达96小时。用秋水仙碱和环己酰亚胺孵育细胞改变了这些蛋白的细胞表面表达。白细胞介素2、4、6和8对细胞表面lamp1和lamp2表达程度的影响较小，尽管它们确实显著影响了淋巴细胞不同亚型之间的表达分布。在本研究使用的条件下，细胞表面LAMP表达主要局限于CD56 + 细胞和CD3 + 细胞。利用基于荧光的黏附试验进行的功能分析表明，细胞表面lamp2介导PBMCs与血管内皮的黏附，可能是通过与内皮选择素相互作用。LAMPs可能有助于体内活化白细胞向炎症部位的迁移。
