Cuomo L, Trivedi P, Wang F, Winberg G, Klein G, Masucci M G
Department of Tumor Biology, Karolinska Institute, Stockholm, Sweden.
Eur J Immunol. 1990 Oct;20(10):2293-9. doi: 10.1002/eji.1830201019.
Epstein-Barr virus (EBV)-negative Burkitt lymphoma (BL) lines are poor stimulators in allogeneic mixed lymphocyte cultures compared to EBV-transformed lymphoblastoid cell lines derived from the same individuals. We have previously shown that the stimulatory capacity of the tumor cells is increased after EBV conversion (Avila-Carino et al., Int. J. Cancer 1987. 40: 691). As a first step towards the identification of the viral gene product responsible for this change we have studied the influence of the EBV latent membrane protein (LMP) on the stimulatory capacity of the EBV-negative BL lines BL41 and DG75 and the B lymphoma line BJAB. Four LMP-transfected sublines of BL41, four DG75 LMP transfectants and one LMP-transfected subline of BJAB showed a significantly stronger stimulatory capacity than the original line. The effect was directly proportional to the amount of LMP detected in each transfectant but was not due to reactivation of LMP-specific memory cells since lymphocytes from EBV-seropositive and -seronegative individuals responded equally. In order to define the relation between LMP expression and induction of stimulatory capacity, DG75 was transfected with constructs containing the LMP gene under the control of an heat-shock promoter. The peak of LMP expression in heat shock-treated cells preceded the appearance of stimulatory capacity by 6-12 h suggesting that critical amounts of the protein may be required to induce the phenotypic change recognized by the T cells. LMP influenced in a dose-dependent manner the expression of the adhesion molecules LFA-1, LFA-3 and ICAM-1 and B cell activation markers CD23 and CD39 in transfected sublines of BL41, but did not affect the expression of these markers in the DG75 and BJAB cell line. All LMP-expressing transfectants showed an increased capacity to form conjugates with unprimed allogeneic lymphocytes.
与源自相同个体的EB病毒（EBV）转化的淋巴母细胞系相比，EBV阴性的伯基特淋巴瘤（BL）细胞系在同种异体混合淋巴细胞培养中是较差的刺激物。我们之前已经表明，EBV转化后肿瘤细胞的刺激能力会增加（阿维拉 - 卡里诺等人，《国际癌症杂志》1987年。40: 691）。作为鉴定负责这种变化的病毒基因产物的第一步，我们研究了EBV潜伏膜蛋白（LMP）对EBV阴性BL细胞系BL41和DG75以及B淋巴瘤细胞系BJAB刺激能力的影响。BL41的四个LMP转染亚系、四个DG75 LMP转染体和BJAB的一个LMP转染亚系显示出比原始细胞系明显更强的刺激能力。这种效应与每个转染体中检测到的LMP量成正比，但不是由于LMP特异性记忆细胞的重新激活，因为来自EBV血清阳性和血清阴性个体的淋巴细胞反应相同。为了确定LMP表达与刺激能力诱导之间的关系，用含有在热休克启动子控制下的LMP基因的构建体转染DG75。热休克处理细胞中LMP表达的峰值比刺激能力的出现提前6 - 12小时，这表明可能需要临界量的该蛋白来诱导T细胞识别的表型变化。LMP以剂量依赖的方式影响BL41转染亚系中黏附分子LFA - 1、LFA - 3和ICAM - 1以及B细胞活化标志物CD23和CD39的表达，但不影响DG75和BJAB细胞系中这些标志物的表达。所有表达LMP的转染体与未致敏的同种异体淋巴细胞形成共轭物的能力都有所增加。
