Why Some Stay Healthy Despite HIV
Finding May Lead to Better AIDS Vaccines
Oct. 7, 2002 -- Hidden in the bodies of a few very special people are the keys to ending the AIDS epidemic. A new study of these rare individuals -- who've never developed AIDS despite 20 years of untreated HIV infection -- may have unearthed the key to an AIDS vaccine.
They're called long-term nonprogressors or LTNPs. All carry the AIDS virus. All remain perfectly healthy without ever taking any AIDS drugs. How do they do it? Nobody is sure, although many years of intensive research have turned up a few clues. One of these clues is that their immune systems feature high numbers of killer white blood cells -- CD8+ T cells -- that destroy virus-infected cells. But nobody has known what to make of this, because people who get sick also make lots of CD8+ cells that recognize HIV.
Now a team of researchers at the U.S. National Institute of Allergy and Infectious Diseases has deployed brand-new technology to compare CD8+ cells from LTNPs with those of other people with HIV infection. What they found changes everything. Team leader Mark Connors, MD; lead author Stephen A. Migueles, MD; and colleagues report their findings in the journal Nature Immunology.
The CD8+ cells from people who get sick just sit there. They make a little noise but don't do much of anything when they encounter HIV-infected cells. In contrast, CD8+ cells from LTNPs get busy in a hurry. They multiply like crazy -- and they make large amounts of a crucial, cell-killing substance called perforin.
The finding may be the Holy Grail of HIV research -- that crucial thing the virus does to the body that makes AIDS a killer disease. Now two big tricks remain.
One is to see what it is that HIV does to CD8+ cells that makes them quit fighting the virus. It's clear that this process involves disturbing the intricate regulation of the immune system. The other trick is to find out what lets LTNPs' overcome the AIDS virus. These keys should unlock the secret to an effective AIDS vaccine. And they hold out hope that such a vaccine might be used to treat people already infected with the virus. -->