MHC is a set of closely linked genes that control the body's ability to identify and reject foreign substances (antigens). In one type of immune response, T cells recognize and destroy antigens. The T cells seem to recognize only antigens associated with MHC proteins.

MHC was first described by pioneer immunologist George Snell in the 1940s. Born in Bradford, Massachusetts in December 1903, and raised in Brookline, Snell chose genetics as a career while studying at Dartmouth College. After receiving his B.S. in 1926, Snell did graduate work in genetics at Harvard University, earning his Ph.D. in biology and immunology in 1930. A fellowship allowed Snell to study genetics for two years at the University of Texas under Hermann Muller. A brief stint at teaching showed Snell that his real interest lay in research; in 1935, he joined the staff of the Jackson Laboratory...