Mhc (Major Histocompatibility Complex)
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 of Bar Harbor, Maine, a center for the study of genetics in mammals that was particularly renowned for its inbred strain of genetically uniform mice. Snell remained at Jackson Lab until his retirement in 1969. At Jackson, Snell became interested in the problem of rejection in organ transplantion. He believed that the ability of one individual to reject tissue from another was strongly affected by genetic factors, which he called histocompatibility (tissue-compatibility) genes (also now known as transplantation genes). He conceived the idea of using the lab's inbred mice to prove his idea. After many generations of cross- and back-cross-breeding, which had to be repeated after a fire at the lab, Snell produced a strain of mice in which he could isolate histocompatibility genes. By 1948, he was able to pinpoint the location on the chromosome of a specific group of genes that played a major role in controlling resistance to tissue grafts. He called this the major histocompatibility complex, or MHC.
Human MHC, called HLA (human leucocyte, or histocompatibility, antigen), was identified by the French immunologist Jean Dausset (1916-) in the 1950s. In 1969, Baruj Benacerraf (1920-) discovered that MHC genes control the body's ability to respond to particular antigens. Benacerraf and others discovered in the mid-1970s that interactions between the body's T cells and B cells during immune responses are dependent on MHC; in order to interact, and therefore produce an effective immune response, both cells must carry the same MHC antigens. Much more remains to be learned about MHC, but its mysteries promise to reveal more about the nature of the immune system and ways to overcome tissue-transplantation rejection. Today human MHC is one of the best-known areas of the human genome, with more than 100 mapped genes.
Snell, Dausset, and Benacerraf shared the 1980 Nobel Prize for physiology or medicine for their discoveries about MHC and its vital role in regulating immunological reactions. Snell died in 1996.
This is the complete article, containing 465 words
(approx. 2 pages at 300 words per page).
