Peter Medawar

British immunologist (1915–1987)

The son of an Englishwoman and a Lebanese businessman trading in Brazil, Medawar was born in Rio de Janeiro and brought to Britain at the end of World War I. He was educated at Oxford, graduating in zoology in 1937, and remained there to work under Howard Florey. His first researches concerned factors affecting tissue-culture growth but during World War II he turned his attention to medical biology. He subsequently developed a concentrated solution of the blood-clotting protein fibrinogen, which could be used clinically as a biological glue to fix together damaged nerves and keep nerve grafts in position.

The terrible burns of many war casualties led Medawar to study the reasons why skin grafts from donors are rejected. He realized that each individual develops his own immunological system and that the length of time a graft lasts depends on how closely related the recipient and donor are. He found that grafting was successful not only between identical twins but also between nonidentical, or fraternal, twins. It had already been shown in cattle that tissues, notably the red-cell precursors, are exchanged between twin fetuses. This led to the suggestion by Macfarlane Burnet that the immunological system is not developed at conception but is gradually acquired. Thus if an embryo is injected with the tissues of a future donor, the animal after birth should be tolerant to any grafts from that donor.

Medawar tested this hypothesis by injecting mouse embryos, verifying that they do not have the ability to form antibodies against foreign tissue but do acquire immunologic tolerance to it. For this discovery Medawar and Burnet were awarded the 1960 Nobel Prize for physiology or medicine.

Medawar moved from Oxford in 1947 to the chair of zoology at Birmingham, a post he held until 1951 when he was appointed professor of zoology at University College, London. In 1962 he accepted the important post of director of the National Institute for Medical Research. For some years he tried to combine his research work with a heavy administrative load. But in 1969 Medawar suffered his first stroke. Although he continued as director until 1971, the stroke had seriously restricted his mobility and dexterity. Despite this he continued his research work on cancer at the Clinical Research Centre, London. A second stroke in 1980, and a third in 1984, brought Medawar's research career to an end.

He continued to write, however, and in 1986 published his autobiography, Memoirs of a Thinking Radish, and collected most of his early essays in Pluto's Republic (1982). It was in one of these essays, first published in 1964, that Medawar characterized science in a much quoted phrase as “the art of the soluble.”

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 coauthor, 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).

For more information on Sir Peter Brian Medawar, visit Britannica.com.

Medawar, Sir Peter Brian (mĕd'əwär) , 1915–87, British zoologist, b. Brazil. After graduate work at Oxford, he held research and teaching posts there. He was professor of zoology (1947–51) at the Univ. of Birmingham and in 1951 became professor of zoology and comparative anatomy at University College, London. During World War II, he discovered a method for joining ends of severed nerves; he later became noted for his experimental work in transplanting living tissue from one body to another. Working on a theory proposed by Sir Macfarlane Burnet, he proved it was possible under certain circumstances for an organism to overcome its normal tendency to reject foreign tissue or organs. Medawar was awarded the 1960 Nobel Prize for Physiology or Medicine jointly with Sir Macfarlane Burnet for this discovery of acquired immunological tolerance. He was knighted in 1965. A prolific writer, his works include The Art of the Soluble (1967), Advice to a Young Scientist (1979), and an autobiography (1986).

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)