X-Message-Number: 11869 Date: Tue, 01 Jun 1999 15:44:43 -0400 From: Jan Coetzee <> Subject: thymus gland. New info. Death-Defying Gland Surprises Medical World: Thymus Tuesday, June 01, 1999 MSNBC NEWS SERVICES - An immune system gland once thought to be inactive in adults actually continues to function late in life, according to research that could lead to new ways of reactivating the natural defenses of AIDS and cancer patients. UNTIL NOW, anatomy experts had concluded the thymus gland, a small, thin organ located behind the breastbone, stopped producing the so-called T-cells of the immune system as individuals aged. In their study, the medical detectives, led by Dr. Beth D. Jamieson of the University of California at Los Angeles (UCLA), determined from a number of tests that the organ continues fielding replacement immune cells in people as old as 56. The research reported Thursday in the journal Immunity suggests that although the gland's productivity slows with age, it remains active nonetheless. "It gives us hope that if we can find ways to boost up the activity of the thymus, we could speed up the replacement of T cells" lost to the AIDS virus, Jamieson said. "There's still a source available for T cells, which was not thought to be the case previously." Drugs also could be developed for cancer patients whose immune systems have been destroyed by chemotherapy. But tests of possible treatments are at least two years away, Jamieson said. THE THYMUS TEST To test the possibility that the thymus keeps educating cells past adolescence, Jamieson's team examined gland tissue from 14 people, either organ donors or individuals who underwent open-heart surgery. The donors ranged in age from 1 to 56. Upon examination, the researchers determined that all the thymus samples contained similar amounts of a marker associated with immature T-cells, indicating that gland tissue produces new disease fighters at all ages. Following this, they added tissue from adult samples to a test tube containing new T-cells. Over six day's time, the cells started displaying the chemical markers of more mature immune cells, whereas a comparison test tube without any of the sample tissue showed no signs of going through the immune-system boot camp. Furthermore, a relatively new T-cell receptor test provided by team members from the University of Texas Southwestern Medical Center in Dallas revealed that blood samples of 45 healthy adults contained brand-new T-cells from the thymus. David Schwartz, professor of molecular microbiology-immunology at the Johns Hopkins School of Public Health, said the study offers important information that will be "very useful for understanding how we can generate new immune responses as we get older." "It means we don't have to rely on T cells that are produced in the first decade of our lives," he said. Previous studies showed that new T cells were being produced by AIDS patients who had been taking potent combinations of AIDS drugs. But it was not known where in the body those cells were being created. OBVIOUS IN HINDSIGHT "It's surprising on one hand, but on the other it seems obvious in hindsight," said Carl Dieffenbach, associate director of the basic science program at the National Institute of Allergies and Infectious Disease in Bethesda, Md. "After all, we'd probably drop dead at age 50 if we didn't get new T-cells from somewhere." He predicts the research will "open up whole new areas of immunology research to treat all kinds of diseases, not just HIV." "In terms of total longevity, who knows," he added. "Perhaps diseases like Alzheimer's have an immune system component we've missed until now, that a more active thymus might correct." The Associated Press and the Medical Tribune News Service contributed to this report. _ Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=11869