The immune system has incredible power to protect us from theravages of infection. Boosted by vaccines, it can protect us fromdiseases such as measles. However, the power of the immune systemis a double-edged sword: an overactive immune system can wreakhavoc, destroying normal tissue and causing diseases such as type Idiabetes, rheumatoid arthritis, and multiple sclerosis. Theconsequences of an impaired immune system, on the other hand, areall too evident in the agonies of AIDS.Packed with illustrations, stories from Dr. William E. Paul'sdistinguished career, and fascinating accounts of scientificdiscovery, Immunity presents the three laws of the humanimmune system—universality, tolerance, and appropriateness—andexplains how the system both protects and harms us. From the taleof how smallpox was overcome and the lessons of the Ebola epidemicto the hope that the immune system can be used to treat or preventcancer, Dr. Paul argues that we must take advantage of cutting-edgetechnologies and promising new tools in immunological research.