AIDS patients survive longer these days, but most still succumb to opportunistic infections that escape an immune system weakened by HIV. Now, however, scientists have evidence that immuno-cell field which stops naturally with age may be able to return to active duty in some people. The discovery, reported in the current Journal of Clinical Investigation , suggests that the body could resume production of certain immune cells after the drug hitter HIV in submission
immune cells called T lymphocytes - . Frontline troops into battle against foreign microbes - are produced in the bone marrow and then battle prepared in the thymus, a small gland at the base of the neck. This training is considered to occur before birth until puberty, when the thymus atrophy and is generally thought to stop functioning. In adulthood, according to most medical textbooks, thymus treated the T cells enough to deal with most microbial invaders one person is likely to encounter in a lifetime. But attacks against HIV destroys T-cells, leaving patients infected defenseless against many pathogens. Nevertheless, some studies have shown that patients on powerful new antiviral therapies seem able to regenerate some of these cells once viral loads were reduced for a sufficient period of time -. Leading researchers to question the source of these new T cells
To see if the thymus may be the source of these new T cells, immunologist Joseph McCune and his colleagues at the Gladstone Institute of Virology and immunology in San Francisco thymus size measured in 99 HIV-positive patients. The team used a technique called computed tomography, which creates an image in three dimensions X-ray of internal organs. About half of the subjects had a much more thymus tissue that HIV-negative controls. In addition, the size of the thymus gland of a subject closely related to blood levels of T cells - indirect proof that the thymus may be working and the release of these immune cells, say the authors
Experts warn that rejuvenation. thymus tissue alone does not prove that the gland is working properly. Yet the results are "a good argument" for a revival of the thymus function, says immunologist Brigitte Autran of the Pitié-Salpêtrière Hospital in Paris, whose team discovered some of the first evidence that immune reconstitution could be possible. "It is clear that the immune system is more difficult to try to raise the number of T cells," adds Mario Roederer, an immunologist at the University of Stanford.
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