immunosenescence

例句：

1. 1.As we age, our immune systems become less effective at fighting off infections.
   随着年龄的增长，我们的免疫系统对感染的抵抗力越来越弱。
2. 2.The elderly often experience a decline in their immune system due to factors such as poor nutrition and lack of exercise.
   老年人由于营养不良和缺乏运动等原因，常常会出现免疫系统下降的情况。
3. 3. Researchers are exploring ways to slow down the process of immunosenescence in order to improve longevity.
   研究人员正在探索减缓免疫衰老进程的方法，以延长寿命。