Abstract
For many years Paul Ehrlich’s theory of horror autotoxicus- that autoimmune disease could not occur - dominated 20th Century thinking. It inhibited acceptance of both clinical and experimental observations testifying to the reality of such a possibility. Then, for almost one halfcentury,immunology lost its medical foundation, and became primarily a chemically oriented discipline. Both of these factors prevented the asking of questions that would have pointed to the importance of immunoregulatory mechanisms in the immune response. Then a variety of biological and medical observations were made in the 1940s and 1950s that demanded a new approach to theory and to experiments. Led by Macfarlane Burnet, an immunobiological revolution took place that made the clarification of cellular and molecular regulatory mechanisms one of the central interests of the new immunobiology.