Sir Peter Brian Medawar OM CBE FRS ( 28 February 1915 - 2 October 1987 ) was a British biologist born in Brazil , whose work on graft rejection and the discovery of acquired immune tolerance was fundamental to the practice of tissue and organ transplants .
Sir Peter Brian Medawar OM CBE FRS ( 28 February 1915 - 2 October 1987 ) was a British biologist .