Watch The Immune System: Your Magic Doctor (1989) : Full Movie Online Free Learn about the body's most important line of defense- the immune system. This film reviews the immune system's various components, showing how they defend the body against invading bacteria and viruses, and also explains what happens when the immune system is not functioning properly. Important factors contributing to the maintenance of a healthy immune system are also discussed. Animation shows how the body stays well, fights disease and heals injuries. Sometimes antibiotics or immunization are needed. Also explains AIDS.