Huard B, Tournier M, Hercend T, Triebel F, Faure F
INSERM U333, Institut Gustave-Roussy, Villejuif, France.
Eur J Immunol. 1994 Dec;24(12):3216-21. doi: 10.1002/eji.1830241246.
The activation requirements for antigen-dependent proliferation of CD4+ T cells are well documented, while the events leading to the inactivation phase are poorly understood. Here, we tested the hypothesis that the lymphocyte-activation gene 3 (LAG-3), a second major histocompatibility complex (MHC) class II ligand, plays a regulatory role in CD4+ T lymphocyte activation. CD4+ class II-restricted T cell clones were stimulated by their relevant antigen (hemagglutinin peptide or diphteria toxoid) and antigen-presenting cells with or without anti-LAG-3 monoclonal antibody (mAb). Kinetic studies were performed to monitor different activation parameters, including the measurement of thymidine incorporation, expression of activation antigens and cytokine secretion. Results showed that the time course from the initial time points up to the peak time point was not modified in the presence of anti-LAG-3 mAb. However, addition of these antibodies, either as whole IgG or as Fab fragments, led to increased thymidine incorporation values for late time points and, hence, to a shift in the decreasing proliferation curve. We also showed that expression of activation antigens, such as CD25, was higher in the presence of anti-LAG-3 mAb, and that cytokine concentrations, i.e. of interferon-gamma or interleukin-4, were higher in the corresponding culture supernatants. In addition, we tested whether the effects of anti-LAG-3 mAb were limited to antigen-dependent, MHC class II-restricted responses. The proliferative responses of CD4+ T cell clones following stimulation with either interleukin-2, mitogens, a combination of anti-CD2 mAb, immobilized anti-CD3 or anti-T cell receptor mAb were not altered by anti-LAG-3 mAb. The allogeneic proliferative response of a CD8+ T cell clone was also not affected. Overall, the present analysis reveals a modulating effect of anti-LAG-3 mAb, mediated specifically on antigen-dependent, MHC class II-restricted responses of CD4+ T cell lines. These results support the view that LAG-3/MHC class II interaction down-regulates antigen-dependent stimulation of CD4+ T lymphocytes.
CD4+ T细胞抗原依赖性增殖的激活要求已有充分记载，而导致失活阶段的事件却知之甚少。在此，我们验证了淋巴细胞激活基因3（LAG-3）这一主要组织相容性复合体（MHC）II类的第二个配体在CD4+ T淋巴细胞激活中起调节作用的假说。用相关抗原（血凝素肽或白喉类毒素）和抗原呈递细胞，在有或没有抗LAG-3单克隆抗体（mAb）的情况下刺激CD4+ II类限制性T细胞克隆。进行动力学研究以监测不同的激活参数，包括胸苷掺入量的测定、激活抗原的表达和细胞因子分泌。结果显示，在存在抗LAG-3 mAb的情况下，从初始时间点到峰值时间点的时间进程没有改变。然而，添加这些抗体，无论是完整的IgG还是Fab片段，都会导致后期时间点的胸苷掺入值增加，从而使下降的增殖曲线发生偏移。我们还表明，在存在抗LAG-3 mAb的情况下，激活抗原如CD25的表达更高，并且在相应的培养上清液中细胞因子浓度，即干扰素-γ或白细胞介素-4的浓度更高。此外，我们测试了抗LAG-3 mAb的作用是否仅限于抗原依赖性、MHC II类限制性反应。用白细胞介素-2、丝裂原、抗CD2 mAb组合、固定化抗CD3或抗T细胞受体mAb刺激后，CD4+ T细胞克隆的增殖反应未被抗LAG-3 mAb改变。CD8+ T细胞克隆的同种异体增殖反应也未受影响。总体而言，目前的分析揭示了抗LAG-3 mAb的调节作用，该作用特异性地介导于CD4+ T细胞系的抗原依赖性、MHC II类限制性反应。这些结果支持LAG-3/MHC II类相互作用下调CD4+ T淋巴细胞抗原依赖性刺激的观点。
