This encyclopedia provides the largest integrated reference source of immunological knowledge that is available. In the six years since the first edition of the Encyclopedia of Immunology was published, there have been astounding advances in many areas of the subject. The second edition of the encyclopedia seeks to encompass these advances and to provide a more up-to-date coverage of the subject as a whole than is now provided by the original text. The large number of the topics covered will be of direct interest not only to experimental and clinical immunologists but also to scientists from many other disciplines, including microbiologists, veterinary surgeons, protein chemists, physiologists, hematologists, and so forth. In addition to being a primary reference source, the encyclopedic format readily lends itself to casual reading with most entries being only two or three pages long.