The immune system is a system inside your body that helps fight against diseases. So when you are sick and you start feeling better that is your immune system fighting germs. The first layer of the layer of immune system is the skin. Their are tiny hairs that collect germs and release the later with a cough or a sneeze. The second line of defense are the antibodies. Antibodies are like small soldiers in your body that kill any germ harmful. The antibodies consists of white blood cells  that kill germs. Of the white blood cells macrophages are the first to go to a germ. Macrophages are everywhere in your body which is why they are the first to reach. Next come the B-cells. B-cells team up with helper T-cells to kill more harmful germs. Last are the killer T-cells. Killer T-cells destroy everything that can be destroyed. When a child, a doctor gives a vaccination to create more white blood cells and antibodies.