This edition: Immunity
All animals have a complex system of physical and chemical defenses to protect them against disease. The first line of defense, surface barriers, is explained in a story about injured birds. As veterinarian Scott Weldy describes how he treats wounded birds of prey, immunologist Edward Golub explains the process of inflammation. Next, the program follows Dr. Jeff Galpin, a survivor of the polio epidemic of the 1950s, who is now a clinical researcher studying the AIDS virus. He explains how specialized T cells (helper and killer T cells) and other blood cells are the frontline soldiers of the immune system. Animation illustrates how macrophages usually engulf potentially harmful viruses and bacteria. Because this is not the case with AIDS, there is a further discussion of T cells, B cells, and antibodies. In the final segment, we investigate an autoimmune disease, lupus, with Dr. Robin Dore. Her patient has an overactive immune system which attacks its own cells, causing chronic inflammation and fatigue. Although the cause of the disease remains a mystery, research continues into how cells recognize self and non-self in order to protect the body against harm.