The British zoologist Peter Brian Medawar (1915-1987) made important contributions to the knowledge of growth, aging, and especially the biology of tissue transplantation.

Peter Medawar was born on Feb. 28, 1915, in Petropolis, Rio de Janeiro, Brazil of a British mother and Lebanese father. He was educated at Marlborough College and subsequently at Magdalen College, Oxford, where he studied zoology and comparative anatomy in the Goodrichian tradition. His early research was concerned with the factors controlling growth in tissue culture. He was greatly influenced in this work by Darcy Thompson, author of Growth and Form. From an early stage in his career Medawar distinguished himself by his competence in both the experimental and the theoretical aspects of biology. He won several prizes at Oxford, where he became a university demonstrator and fellow of Magdalen College.

During World War II Medawar investigated the repair of peripheral nerve injuries. In one of these investigations he devised the first biological "glue," which he used to reunite severed nerves and to fix grafts. This work stimulated his interest in the techniques for transplantation. In 1942 Medawar turned his attention to skin grafts as a result of the need to replace skin after severe burns. He demonstrated that grafts from unrelated donors (homografts) are normally destroyed as a consequence of an immunological response--the homograft reaction--on the part of the host. He was determined then to break down this homograft barrier.

In 1948, when only 32, Medawar was appointed Mason professor of zoology at Birmingham University. A year later he was elected a fellow of the Royal Society. At Birmingham he became interested in problems of cellular heredity and transformation and renewed his attack on the homograft problem. While attempting to devise a method to distinguish between identical and fraternal cattle twins by exchanging skin grafts between twin pairs, he discovered that even fraternal twins of unlike sex would accept each other's grafts. From this he hypothesized that an exchange of cells between the cattle before birth brought about graft tolerance after birth.

In 1951, when Medawar moved to the Jodrell chair of zoology at University College, London, he followed the lead afforded by the cattle work and demonstrated that inoculation of very young mice with cells from unrelated donors created a tolerance to homografts from their donors later in life. Apart from establishing that the homograft problem was in principle soluble and providing a great impetus to research to this area, this finding introduced a new concept into immunology, that of acquired immunological tolerance. For this work Medawar received a Nobel Prize in 1960. He also succeeded in extracting from cells the antigens capable of eliciting transplantation immunity, thus setting the stage for further biochemical studies. He also demonstrated that homograft reactivity is a form of delayed allergy.

In 1962 Medawar was appointed director of the National Institute for Medical Research at Mill Hill. Undaunted by administrative responsibilities, he continued to work energetically in his laboratory. Wherever he worked Medawar attracted a dedicated group of students and research fellows. With characteristic generosity he treated them as colleagues and collaborators, and from the beginning he gave them unstinting help and encouragement. Many former members of his "school" went on to occupy distinguished positions around the world. His many recognitions and awards included a knighthood and numerous honorary degrees. Throughout the 1970s and 1980s, Medawar produced several books, some with his wife as co-author, in addition to his many essays on growth, aging, immunity, and cellular transformations. In one of his most popular books, Advice to a Young Scientist, Medawar wrote that scientists are not geniuses, merely people with common sense and curiosity. He died on Oct. 2, 1987, at the age of 72.

Further Reading

• For sketches of Medawar's life and work see Sir Peter Medawar (1915-1987) by N.A. Mitchison in Nature (Nov. 12, 1987); J.S. Medawar's A Very Decided Preference: Life with Peter Medawar (1990); the Nobel Foundation, Physiology or Medicine: Nobel Lectures, Including Presentation Speeches and Laureates' Biographies (3 vols., 1964-1967), and Theodore L. Sourkes, Nobel Prize Winners in Medicine and Physiology, 1901-1965 (rev. ed. 1967).