Posted by Sandy Donchess on October 27, 1999 at 21:07:33:
Wednesday October 27 2:02 PM ET
Scientists Decipher Immunity Genes
By ALEX DOMINGUEZ Associated Press Writer
Scientists have deciphered a part of the human genetic code that plays a key role in the body's immune system, an accomplishment that could lead to improvements in organ transplants as well as in fighting disease.
The researchers identified the 3.6 million building blocks of DNA in the major histocompatibility complex, or MHC. Genes in the complex help immune system cells work together to fight off disease and recognize the body's own tissue as friend and not foe.
Now that the entire sequence is known, transplant centers might eventually be able to find donor organs that more closely match the recipient's genetic code. That might reduce the risk of organ rejection.
``It would be a bit hard to overstate the importance of understanding this set of genes,'' said Elbert Branscomb, a geneticist at the Lawrence Livermore National Laboratory in California who was not involved in work.
The work was reported in Thursday's issue of the journal Nature by scientists from the United States, Britain and Japan.
Scientists have traced many diseases to genes in the MHC - more diseases, in fact, than are linked to any other region of the human genetic code.
There are several reasons for this. The MHC contains a lot of genes, about 400, which allows many chances for error. Also, the region is easy to inspect for disease-promoting genes. And the MHC's job description means flaws in its genes can cripple the body's defenses against some germs, or mistakenly prod the immune system into causing disease by attacking the body's own tissues.
``Diabetes is an example. In some forms it's caused when the immune system attacks cells in the pancreas,'' said co-author Daniel Geraghty, a geneticist at the Fred Hutchinson Cancer Research Center in Seattle.
The new work will help scientists understand diseases brought on by a faulty immune system attack and learn how the body can resist infectious diseases, researchers said. That could lead to new treatments.
While scientists have been studying the MHC for years, the new work shows the region contains more genes than previously thought, Branscomb said.