Augustin M, Dietrich A, Niedner R, Kapp A, Schöpf E, Ledbetter J A, Brady W, Linsley P S, Simon J C
Department of Dermatology, University of Freiburg, Germany.
J Invest Dermatol. 1993 Mar;100(3):275-81. doi: 10.1111/1523-1747.ep12469748.
In previous studies, Phorbol-12-myristate-13-acetate (PMA)-treated human keratinocytes (PMA-HNK) were shown to induce T-cell proliferation via a major histocompatibility complex (MHC)- and antigen (Ag)-independent mechanism, that was mediated in part by PMA-induced intercellular adhesion molecule (ICAM)-1 on HNK. Recently, the interaction of the B7 Ag on antigen-presenting cells with its ligand CD28 on T cells has been shown to deliver activation signals distinct from the interaction of MHC/Ag with the T-cell receptor. These findings led us to assess whether B7-dependent signals play a role in T-cell proliferation induced by PMA-HNK. We first examined B7 expression on HNK by staining with three different monoclonal antibodies (MoAbs). When analyzed by fluorescence-activated cell sorter, untreated HNK stained only faintly. By contrast, PMA induced a dose-dependent upregulation of B7 staining. This staining identifies a molecule closely related to B7 because it was blocked by purified recombinant B7 immunoglobulin. Upregulation of B7 staining was first observed 16 h after PMA treatment and persisted for at least 48 h; it was protein kinase C dependent and required de novo protein synthesis. Anti-B7 MoAbs reduced specifically the capacity of PMA-HNK to trigger proliferation of allogeneic peripheral blood mononuclear cells and T cells. The combination of anti-B7 and anti-ICAM-1 MoAbs further reduced this response. We conclude that PMA upregulates on HNK the expression of a B7-like molecule that contributes in concert with ICAM-1 to the capacity of PMA-HNK to induce proliferation of allogeneic T cells.
在先前的研究中，佛波醇-12-肉豆蔻酸酯-13-乙酸酯（PMA）处理的人角质形成细胞（PMA-HNK）被证明可通过主要组织相容性复合体（MHC）和抗原（Ag）非依赖性机制诱导T细胞增殖，该机制部分由PMA诱导的HNK上的细胞间黏附分子（ICAM）-1介导。最近，抗原呈递细胞上的B7抗原与其T细胞上的配体CD28之间的相互作用已被证明可传递不同于MHC/Ag与T细胞受体相互作用的激活信号。这些发现促使我们评估B7依赖性信号是否在PMA-HNK诱导的T细胞增殖中起作用。我们首先用三种不同的单克隆抗体（MoAb）染色来检测HNK上的B7表达。通过荧光激活细胞分选仪分析时，未处理的HNK仅微弱染色。相比之下，PMA诱导了B7染色的剂量依赖性上调。这种染色鉴定出一种与B7密切相关的分子，因为它被纯化的重组B7免疫球蛋白阻断。B7染色的上调在PMA处理后16小时首次观察到，并持续至少48小时；它依赖于蛋白激酶C且需要从头合成蛋白质。抗B7单克隆抗体特异性降低了PMA-HNK触发同种异体外周血单个核细胞和T细胞增殖的能力。抗B7和抗ICAM-1单克隆抗体的组合进一步降低了这种反应。我们得出结论，PMA上调HNK上一种B7样分子的表达，该分子与ICAM-1协同作用，有助于PMA-HNK诱导同种异体T细胞增殖的能力。
