One of the main attractions of research into hypersensitivity disorders is that it brings together scientists from a very broad range of disciplines. As the most common hu- man immunologic disorder, it excites the interest and concern of clinicians, geneticists, basic and clinical immunologists, molecular biologists, biochemists, and physiologists. General agreement has been forged on the the pathophysiology of the disease and the mechanisms responsible for its maintenance, but many areas remain as black boxes for which we have only hypotheses. In 1992 Vienna hosted an international symposium...