This is the fourth edition of a well-established dictionary of Immunology which has been completely revised and updatedto include key terms arising from new discoveries in the fast-developing fields of molecular and cellular immunology. It also contains brief descriptions of the most commonly used immunological techniques, as well as definitions, useful in clinical immunology, of immunodeficiency states, autoimmune diseases etc. Clear illustrations and tables have been added to illustrate the text where appropriate. The book should be readily understandable by anyone with a background in biology and many of the definitions should be understandable to the general reader, especially as terms are extensively cross-referenced.It should be useful to those attending immunological meeting or reading immunological journals, especially as scientists communicating to specialized audiences rarely define their terms.It will also be invaluable to undergraduate and postgraduate students in biological and medical sciences, since immunological methods, such as use of monoclonal antibodies, are in wide use throughout biology and medicine.