Photocontrolled Immune Responses using Photochromic Antigen

抗原-抗体反应的主要特征之一是其精确的分子识别，即使是抗原结构的微小变化也可以区分。这种精确的分子识别对于技术以及医学科学中的许多应用是有用的。制备了针对带有光致变色偶氮苯部分（Glu-azoAla-Gly-Gly，azoAla=L-p-phenylazophenylalanine）的四肽的单克隆抗体。当偶氮苯部分为反式时，抗体结合半抗原肽，但释放顺式肽。利用脉冲激光研究了光可逆结合和释放的机理。发现半抗原肽的光异构化发生在结合位点内部，表明后者具有足够的柔性，可以在几十皮秒内发生反-顺光异构化。此外，我们制备了抗光致变色抗原的T细胞杂交瘤。利用这些光致变色T细胞杂交瘤，我们研究了T细胞和抗原呈递细胞之间的相互作用，共聚焦荧光显微镜。发现抗原呈递引起T细胞杂交瘤中活化驱动的细胞死亡（凋亡）。这些结果表明，通过使用这些T细胞杂交瘤系统，能够光控制T细胞中的凋亡。

One of the major characteristics of antigen-antibody reactions is their precise molecular recognition that can distinguish even a small change in the antigen structure. This precise molecular recognition is useful for many applications in technology as well as in medical sciences. Monoclonal antibodies against a tetrapeptide carrying a photochromic azobenzene moiety (Glu-azoAla-Gly-Gly, azoAla=L-p-phenylazophenylalanine) were prepared. The antibodies bind the hapten peptide when the azobenzen moiety is in the trans form, but release the peptide in the cis form. The mechanism of photoreversible binding and release was studied using a pulse laser light. Photoisomerization of the hapten peptide was found to occur inside the binding site, indicating thatthe latter is flexible enough to allow the trans-cis photoisomerization wthin a few ten picoseconds. Further, we prepared T-cell hybrodomas against photochromic antigen. Using these photochromic T-cell hybridomas we studied the interaction between T cell and antigen-presenting cells by confocal fluorescence microscopy. It was found that antigen presentation caused activation-driven cell death (apoptosis) in T-cell hybridomas. These results indicated that apoptosis in T cells are able to be photocontrolled by using these T-cell hybridoma systems.