Important note: Information in this article was accurate in 2002. The state of the art may have changed since the publication date.
|
|
Wall Street Journal - May 14, 2002
Marilyn Chase, Staff Reporter Of The Wall Street Journal
NK cells are white blood cells of the immune system that ordinarily provide a first-line defense against invaders such as viruses and cancers, arriving on the scene faster than antibodies or other members of the immune defense team. But, researchers discovered, some NK cells get infected by HIV. To make matters worse, NK cells have the power to resist treatment by draining themselves of protease inhibitors, a key ingredient of AIDS drug cocktails. This mechanism may help the infected cells survive as a permanent reservoir of virus in the bodies of AIDS patients.
The sobering findings are published Tuesday in the Proceedings of the National Academy of Sciences by Antonio Valentin and George Pavlakis of the National Cancer Institute, a unit of the National Institutes of Health in Bethesda, Md. The work was done in collaboration with scientists at the Aaron Diamond AIDS Research Center, Rockefeller University, the University of Athens, Greece, and the Red Cross General Hospital of Athens in Greece.
Infected NK cell reservoirs were found in the blood of AIDS patients after one to two years of highly active antiretroviral treatment, as the drug cocktails are known. This first report of finding HIV hidden inside NK cells is the product of an intensive hunt, said Dr. Pavlakis in an interview. As recently as two years ago, "an immunologist told me they didn't exist, to forget about it. So it was unexpected." "NK cells," he added, "are important in organizing first-line defenses against infection by pathogens and are important for the defense against cancer. They look around for abnormal cells and kill them. These are the police force, and if they get infected it's a difficult situation. They may be difficult cells to eliminate."
Ferreting out all the hiding places of HIV is a continuing quest. Scientists have long known AIDS takes refuge in other cells of the immune system, such as CD4-positive T-cells, which orchestrate the immune response, and monocyte macrophage cells, which gobble up infected cells. NK cells are a third major class of cells to fall prey, and many expect more to be found.
"It's yet another reservoir we need to contend with," said Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, Bethesda, Md., and a leader in exploring how AIDS penetrates and subverts the human immune system. This additional puzzle piece, he added, "underscores the complexity of HIV, and its ability to persist in hosts despite therapy."
Such reservoirs may help to explain why even the newest drug treatments can fail in some patients. "In the future, I imagine what we have to do is to devise cocktails that take care of any cells, including the Natural Killer cells, that have the ability to be resistant," Dr. Pavlakis said.
He stresses, however, that further research is needed, and that patients shouldn't revise their drug regimens on the basis of a preliminary finding.
Many mysteries surrounding the NK cells remain to be solved. Ordinarily, the type of NK cells vulnerable to HIV comprise just 1% to 5% of all Natural Killer cells. "Interestingly, what happens in AIDS patients is that there is a great increase in NK cells," said Dr. Pavlakis. "We don't know why."
Write to Marilyn Chase at marilyn.chase@wsj.com
020514
WJ020504
Copyright © 2002 - The Wall Street Journal. Reproduction of this article (other than one copy for personal reference) must be cleared through the WSJ Permissions Desk.
AEGiS is a 501(c)3, not-for-profit, tax-exempt, educational corporation. AEGiS is made possible through unrestricted funding from Boehringer Ingelheim, Bridgestone/Firestone Charitable Trust, Elton John AIDS Foundation UK, the National Library of Medicine, AIDS Walk of Orange County, and donations from users like you.
Always watch for outdated information. This article first appeared in 2002. This material is designed to support, not replace, the relationship that exists between you and your doctor.
AEGiS presents published material, reprinted with permission and neither endorses nor opposes any material. All information contained on this website, including information relating to health conditions, products, and treatments, is for informational purposes only. It is often presented in summary or aggregate form. It is not meant to be a substitute for the advice provided by your own physician or other medical professionals. Always discuss treatment options with a doctor who specializes in treating HIV.
Copyright ©1980, 2002. AEGiS. All materials appearing on AEGiS are protected by copyright as a collective work or compilation under U.S. copyright and other laws and are the property of AEGiS, or the party credited as the provider of the content. .