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能区分开来。这种精确的分子识别在技术和医学科学的许多应用中都是有用的。制备了抗偶氮苯光致变色部分四肽(Glu-azoAla-Gly-Gly，azoAla=L-对苯偶氮苯丙氨酸)的单抗。当偶氮苯部分以反式形式存在时，抗体结合半抗原肽，但以顺式形式释放多肽。利用脉冲激光研究了光可逆结合和释放的机理。半抗原肽的光致异构化发生在结合部位内，表明后者足够灵活，可以在几十皮秒内进行反式光致异构化。此外，我们还制备了抗光变色抗原的T细胞杂交瘤。利用这些光致变色T细胞杂交瘤，我们用共聚焦荧光显微镜研究了T细胞与抗原提呈细胞之间的相互作用。研究发现，在T细胞杂交瘤中，抗原提呈可引起活化诱导的细胞死亡(即细胞凋亡)。这些结果表明，利用这些T细胞杂交瘤系统能够光控制T细胞的凋亡。

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.