Basic Analysis of Immuno-gene Therapy for Melanoma Using Functional Characteristic of CD82

为了确定在T细胞活化的早期阶段起作用的T细胞共刺激分子，我们建立了抑制或增强组织细胞白血病细胞系U937的T细胞活化的单克隆抗体（mAb）。通过表达克隆，鉴定了识别T细胞和U937的mAb之一53 H5与CD 82结合。CD 82的功能分析表明：1）CD 82需要同时存在于T细胞和U937上才能完全激活T细胞; 2）通过刺激如CD 3连接或PMA处理，CD 82在T细胞和U937上的表达上调; 3）CD 82的过表达增强T细胞与U937之间的同型和异型细胞粘附; 4）CD 82信号共刺激T细胞，并且该信号与CD 28介导的T细胞共刺激信号协同作用; 5）在使用U937作为刺激细胞的混合白细胞反应（MLR）中，U937上的CD 82过表达与U937细胞的较高同种异体性相关; 6）黑素瘤细胞上的CD 82过表达增强黑素瘤细胞与T细胞之间的异型细胞粘附。这些结果表明，CD 82在T细胞和抗原呈递细胞或靶细胞上均表达，不仅作为T细胞中的共刺激分子，而且作为细胞粘附分子发挥重要作用。

To define T-cell costimulatory molecules that work in the early phase of T-cell activation, we established monoclonal antibodies (mAbs) that inhibit or enhance T-cell activation by histiocytic leukemia cell line U937. One of the mAbs, 53H5, that recognized both T cells and U937 was identified to bind to CD82 by expression cloning. Functional analyses of CD82 revealed the following : 1) CD82 needs to exist on both T cells and U937 for the full activation of T cells ; 2) CD82 expression is up-regulated on both T cells and U937 by stimulation such as CD3 ligation or PMA treatment ; 3) overexpression of CD82 enhances both homotypic and heterotypic cell adhesion between T cells and U937 ; 4) CD82 signal costimulates T cells and the signal works synergistically with the CD28-mediated T-cell costimulation signal ; 5) in mixed leukocyte reaction (MLR) using U937 as stimulator cells, CD82 overexpression on U937 correlates with the higher allogeneicity of U937 cells ; 6) overexpression of CD82 on melanoma cells enhances heterotypic cell adhesion between melanoma cells and T cells. These results indicate that CD82, expressed on both T cells and antigen presenting cells or target cells, plays an important role not only as a costimulatory molecules in T cells, but also as a cell adhesion molecules.