Benacerraf, Baruj, 1920-, American immunologist, b. Caracas, Venezuela, grad. Columbia Univ. (1942). Raised in Paris, he came to the United States at the outset of World War II. He earned his M.D. in 1945 and worked (1950-56) as a researcher in Paris before becoming a professor at New York Univ. (1957-68) and Harvard (1970-). His research led to the discovery of genetic structures that regulate immunological responses, for which he shared (with George Snell and Jean Dausset) the 1980 Nobel Prize in Physiology or Medicine.