1. The first line of defense: the skin and mucous membrane barrier. Before the virus invades the human body, the skin and mucosa of the human body will form a barrier to prevent the virus from entering the body.
2. The second line of defense: immune cells. Once the virus has conquered the first line of defense, the immune system will intervene, especially phagocytes (such as macrophages), which will destroy the source of infection by swallowing and digesting the virus.
3. The third line of defense: antibodies. When immune cells remove viruses, the body will produce corresponding antibodies, which can recognize and resist the invasion of similar viruses, thus maintaining immunity.
4. Immune memory. Once the body produces a specific antibody, it will form an immune memory, and when the same virus invades again, the body will identify and remove the intruder more quickly.
In short, the immune system can protect the human body from influenza virus through various defense mechanisms, providing effective protection for the human body.