DOHERTY, PETER C.

born Oct. 15, 1940, Australia Australian immunologist and pathologist who, with Rolf Zinkernagel of Switzerland, received the Nobel Prize for Physiology or Medicine in 1996 for their discovery of how the body's immune system distinguishes virus-infected cells from normal cells. Doherty earned bachelor's (1962) and master's (1966) degrees in veterinary medicine from the University of Queensland but switched to pathology while earning his doctorate (1970) from the University of Edinburgh, Scot. While conducting research (197275) at the John Curtin School of Medical Research in Canberra, Doherty began collaborating with Zinkernagel in studying what role the white blood cells known as T lymphocytes (T cells) play in mice infected with a particular type of virus able to cause meningitis. They theorized that it was the strength of the immune response itself that caused the fatal destruction of brain cells in mice infected with this virus. To test this theory, they mixed virus-infected mouse cells with T lymphocytes from other infected mice. The T lymphocytes did destroy the virus-infected cells, but only if the infected cells and the lymphocytes came from a genetically identical strain of mice; the T lymphocytes would ignore virus-infected cells that had been taken from another strain of mice. Further research showed that T cells must recognize two separate signals on an infected cell before they will destroy it. One signal is a fragment of the invading virus that the cell displays on its surface; the other is a self-identifying tag from the cell's major histocompatibility complex (MHC) antigens, which identify a cell as belonging to one's own body. This concept of the simultaneous recognition of both self and foreign molecules formed the basis for a new understanding of the general mechanisms used by the immune system at the cellular level. After teaching at the Wistar Institute in Philadelphia, Pa. (197582), Doherty headed the department of pathology at the Curtin School in Canberra (198288) and became chairman of the department of immunology at St. Jude Children's Research Hospital in Memphis, Tenn., in 1988.