A system out of balance --; Basic immunology --; Checks and balances --; The heart of darkness : why did the immune system evolve? --; Emergence of an autonomous immune system --; Autoimmunity : the curse of immunological intolerance --; Immunity under stress --; Mind, brain, and body --; Chemicals that poison immunity --; Cancer and the immune system --; Motherhood and immunity --; Ultraviolet light and skin immunity --; HIV : the scourge of immunity --; Unanticipated features --; Building on natural immunity : the vaccine story --; The Tao of the immune system.