抗原

例句：

1. 1. Thestudy of the structure and function of antigens is crucial for understanding disease mechanisms.
   研究抗原的结构与功能对于理解疾病机制至关重要。
2. 2. Antibodies are proteins that recognizeand bind to antigens.
   抗体是识别并结合抗原的蛋白质。
3. 3. Theimmune system uses antibodies tofight off foreign invaders,such as viruses and bacteria.
   免疫系统使用抗体来对抗外来入侵者，如病毒和细菌。