Peter Brian Medawar, Prêmio Nobel de Medicina e Fisiologia em 1960, era brasileiro, nascido no Hospital Santa Teresa, em Petrópolis, onde viveu até os 14 anos de idade ao lado de seus pais, que permaneceram na cidade por 40 anos, sempre morando na rua João Caetano, no bairro do Caxambu.

Alguns Medawar deixaram o Líbano no início de 1900 para viver no Brasil. Edmond Medawar foi um deles. Seu irmão Nami Medawar, no entanto, o pai de Peter, foi para a Inglaterra, onde tornou-se cidadão inglês e proprietário de uma indústria de material ótico e dentário. Em 1913, ainda solteiro, Nami resolveu fechar sua firma em Londres e vir para o Brasil com seus parentes. No Rio de Janeiro, abriu a Ótica Inglesa, que funciona até hoje na rua Sete de Setembro, logo atrás da Igreja de São Francisco. Pouco depois, Nami conheceu Edith Darling, uma inglesa, com quem se casou indo morar em Petrópolis. Na cidade da serra fluminense, o casal teve três filhos: Philip, Pámela e Peter, que nasceu em 28 de fevereiro de 1915. Peter se educou na cidade e viveu sua infância e juventude como qualquer moço de seu tempo, sempre se destacando como ótimo aluno. Empolgado com o êxito escolar do filho, Nami mandou-o para a Inglaterra, onde o rapaz prosseguiu seus estudos. Ele tinha então 14 anos. Poucos anos depois, Peter ingressava na Universidade de Oxford, onde se bacharelou em zoologia no ano de 1932 pelo Magdalen College, um renomado centro científico com cinco séculos de existência. Em sua permanência na instituição, trabalhando a convite, Peter interessou-se por biologia relacionada à medicina. Nos anos seguintes, apresentou trabalhos científicos desenvolvendo uma técnica de ligadura de terminais nervosos que lhe permitiu prestar exames e se tornar um pesquisador do Magdalen College. Era então o mais jovem em sua categoria em Cambridge, segundo seu primo Gerdal Medawar, empresário no Rio de Janeiro.   Foi nessa época que Peter teria de voltar ao Brasil para prestar o serviço militar obrigatório. Decidido a não interromper suas pesquisas, pediu a seu pai que tentasse torná-lo isento dessa obrigação para não perder a cidadania brasileira. Nami Medawar apelou para Salgado Filho, então ministro da Aeronáutica. Negado o pedido, e sem outra saída, o jovem pesquisador foi obrigado a tornar-se cidadão britânico. Peter Medawar teve uma destacada carreira acadêmica como professor e pesquisador, passando por todos os colleges de sua área em Oxford. Trabalhou também como jodrel professor e como mason professor na Universidade de Birmingham. Na London University, foi indicado como jodrel professor em zoologia e anatomia comparada, período em que desenvolveu profundos estudos sobre a forma e a simetria nos animais e nas plantas. Mas seu interesse maior concentrou-se nos transplantes de tecidos vivos, uma tentativa milenar que desde 1949 tinha dado um considerável salto com a publicação de um trabalho imunológico de Frank Burnet, notável pesquisador australiano e parceiro de trabalho de Peter. Em paralelo a suas pesquisas, Medawar desempenhava também atividades didáticas e administrativas. No ano de 1962, tornou-se diretor do Instituto Britânico de Pesquisas Médicas, mesmo não sendo clínico nem médico.

A consagração

O Prêmio Nobel veio em 1960, em parceria com sir Frank Burnet, 16 anos mais velho que Medawar – e considerado pela editora The Times um dos “Mil Homens que Fizeram o Século 20” por suas pesquisas em diversas áreas. Burnet iniciou uma pesquisa com anticorpos, formulando conclusões que depois seriam comprovadas por Medawar. O cientista petropolitano também pesquisava transplante de tecidos vivos entre indivíduos, já tendo concluído que em certas circunstâncias surgia uma força biológica que inibia a rejeição do organismo hospedeiro, mesmo não reconhecendo os antígenos estranhos. Muitos pesquisadores rejeitaram essa conclusão, mas Burnet propôs que continuassem juntos a pesquisa.

A questão básica era saber como se fabricavam os anticorpos – altamente específicos – para então lidar com cada um deles. Até 1955, achava-se que a substância transplantada produzia esses anticorpos de alguma forma. Foi então enunciada a Teoria da Seleção Clonal, que dizia que esses anticorpos estavam presentes nos linfócitos do sangue. Percebeu-se então que, quando um antígeno estranho se unia ao anticorpo de um linfócito, a célula iniciava sua multiplicação, produzindo grandes quantidades desse anticorpo. Esses foram os primeiros passos para que os transplantes se tornassem possíveis 30 anos depois. A teoria ficou conhecida como Tolerância Imunológica Adquirida, trabalho que levou o “jovem petropolitano e fisiologista inglês” Medawar a receber o reconhecimento oficial da Rainha Elizabeth, que o nomeou cavaleiro do Reino Unido em 1965 com o título de sir Peter Brian Medawar. O cientista chegou a retornar ao Brasil em 1962 para visitar parentes, ocasião em que participou de encontros científicos e palestras. A Fiocruz, no Rio, mantém um registro de sua presença e atividade na entidade. Medawar morreu em 1987.

Peter Brian Medawar was born on February 28, 1915, in Rio de Janeiro. He is the son of a business man who is a naturalized British subject, born in the Lebanon. Medawar was educated at Marlborough College, England, where he went in 1928. Leaving this College in 1932, he went to Magdalen College, Oxford, to study zoology under Professor J. Z. Young. Medawar's earlier research, done at Oxford, was on tissue culture, the regeneration of peripheral nerves and the mathematical analysis of the changes of shape of organisms that occur during this development. During the early stages of the Second World War he was asked by the Medical Research Council to investigate why it is that skin taken from one human being will not form a permanent graft on the skin of another person, and this work enabled him to establish theorems of transplantation immunity which formed the basis of his further work on this subject. When he moved to Birmingham in 1947 he continued to work on it, in collaboration with R. Billingham, and together they studied there problems of pigmentation and skin grafting in cattle, and the use of skin grafting to distinguish between monozygotic and dizygotic twins in cattle. In this work they took into consideration the work of R. D. Owen and concluded that the phenomenon that they called «actively acquired tolerance» of homografts could be artificially reproduced. For this earlier work on transplantation and growth, Medawar was elected a Fellow of the Royal Society, London. When he moved to London in 1951, Medawar continued to work with R. Billingham and L. Brent, on this phenomenon of tolerance, and his detailed analysis of it occupied him for several years. He also carried out other researches into transplantation immunity.
The Royal Society of London, where he was the Croonian Lecturer in 1958, awarded him the Royal Medal in 1959. In the same year, he was Reith Lecturer for the British Broadcasting Corporation. He has been elected a Foreign Member of the New York Academy of Sciences, the American Academy of Arts and Sciences, and the American Philosophical Society.In 1937 Medawar married Jean Shinglewood Taylor, daughter of a Cambridge physician. They have two sons, Charles and Alexander, and two daughters, Caroline and Louise.  

Oxford Education

Peter Medawar graduated with a First. Because his interest was well kindled in zoology, he stayed on as a graduate student at Oxford. He plunged into research on embryos, using the then revolutionary technique of culturing cells. His first studies identified a compound in malt extract that inhibited connective tissue cells in culture. He showed the first draft of his manuscript describing the research to Howard Florey, the discoverer of penicillin. Florey pulled no punches in denouncing the paper, saying that "it sounds more like philosophy than science." Despite the criticism, Florey encouraged him to fix the paper and to pursue his line of research, putting him in touch with chemists with whom he could consult to learn more about the mysterious inhibitory compound. Peter never identified the chemical nature of this compound. In the meantime, he did use the malt extract to study the mathematics that describe growth of cell in culture.
While conducting his research, Peter also worked in Florey's laboratory, where everyone studied wound and burn healing to aid in the World War II effort in Britain. At that time, people with severe burns were kept alive with blood transfusions and sulfa drugs to combat infections. This created a problem as the burned tissue would fall away and leave in its place raw areas that were very vulnerable to infection. Peter tested a variety of antibacterial substances, finding that some of the sulfa drugs were effective when applied as a powder to the raw areas. In a tissue culture, one sulfa drug's crystals actually enhanced the ability of epithelial cells to spread, using the crystals as a support "pole" for tent-like coverings. Thus, this drug not only reduced infections but also accelerated the covering of raw burn areas by new skin growth.
These war wound experiences also shaped Peter's future research. He became intrigued with the fact that skin grafts only worked if the grafted skin came from the same person receiving the graft. Somehow, the body could recognize alien tissue and would not accept it. How? He took on this problem as his "duty and pleasure" to investigate. As World War II continued in Europe, he applied for and received a grant to study the issue in a surgical unit where there were plenty of patients with skin wounds needing grafts.
One of his first clues was the observation that a second graft of "foreign" skin did not last as long as the first one. This suggested that the body had some kind of memory of the first graft experience. He and his colleague, Tom Gibson, published a paper on the data and concluded that the body has a mechanism that resists alien tissue, much like the mechanism by which the body resists other foreign invaders, such as bacteria, viruses, and parasites. The mechanism allows the body to adapt to or reject foreign intrusion. Moreover, the resistance system can retain a residual memory and respond even more vigorously at the second time of exposure.
Peter then embarked on a large program involving animal testing of skin-graft rejection. He cut and stained tissue samples taken from the grafts and observed cellular changes occurring at various stages of graft rejection. Because the war was in full sway, Peter had little help. He was responsible for all of the animal feeding, surgeries, nursing care, and laboratory work. He felt guilty if he did less, though he took some comfort from the fact that he was helping to develop treatments for war injuries. He was also proud to be teaching medical students who would become the doctors saving lives during the war. He acquired the habit of working long days and bringing home a briefcase of documents to read before the next morning.
Peter's most important work was to demonstrate that the rejection of donor grafts was due to an immunological reaction and that tolerance could be built up by injections into embryos. Thus was born the idea of acquired immunological tolerance, an idea that is still spawning new research to this day, because how this tolerance develops is still not fully understood. The body's capacity for reacting to foreign proteins can be reduced by repeated exposure to the protein, preferably in small, graded amounts.  Applications of Peter Medawar's research include the common practice of treating allergies with allergy shots and of reducing rejection of tissue transplants. Although most of his work was immediately accepted and appreciated by his peers, Peter is often quoted for the famous quip:
The human mind treats a new idea the way the body treats a strange protein -- it rejects it.
For his important discoveries, Peter was awarded the Nobel Prize in 1960. It was his research on tissue transplantation which eventually helped make organ transplants possible.