Important note: Information in this article was accurate in 1997. The state of the art may have changed since the publication date.
The Associated Press; 50 Rockefeller Plaza, New York, NY 10020 - Thursday, November 20, 1997; 4:59 p.m. EST
Paul Recer, AP Science Writer
An analysis of blood from a Boston man infected with HIV for 18 years but still healthy showed that he was protected by a large number of immune system cells, called helper T-cells, that specifically attack the AIDS virus.
Most patients with long-term HIV infection have a low supply of helper T-cells targeting the AIDS virus, which leaves the immune system defenseless against the virus, Dr. Bruce Walker of the Massachusetts General Hospital said. He is senior author of a study being published Friday in the journal Science.
"Our work provides an explanation of why a very small group of people have been able to avoid getting sick from this virus even though they are infected," said Walker.
Helper T-cells direct the body's immune system. A variety of the cells exist, and each type is primed to attack a specific virus or other invader. As these cells detect the presence of a target virus, they reproduce by the billions, flooding the bloodstream with defenders.
But HIV, the AIDS virus, has broken down this defense. For reasons not understood, helper T-cells specific for HIV often are at low levels in or absent from patients infected with the virus.
Experiments at Massachusetts General confirmed that high levels of HIV-specific T-cells may be essential for the body to hold the AIDS virus in check.
Walker said laboratory tests of blood from HIV patients found that those with the strongest T-cell response to the HIV antigen had the lowest amount of virus in their bloodstream, but those with weak T-cell responses had high virus loads.
The discovery suggested the body might be able to control HIV if helper T-cells that target the virus could somehow be protected.
To test this idea, researchers used powerful anti-viral drugs to treat patients recently infected with HIV. Walker said the drugs caused the virus load to drop quickly, and the patients' immune systems then started producing T-cells that specifically attacked HIV.
Walker said the HIV-specific T-cells were not produced in the bodies of patients who had been infected with HIV for more than six months.
"This suggests that there is a window of time during the acute phase of infection when anti-viral treatment can rescue the helper T-cell response to HIV," Walker said. If treatment is delayed, he said, that natural protection may be lost forever.
Dr. David H. Schwartz, a Johns Hopkins University AIDS researcher, said the Massachusetts General finding confirms work performed earlier at Hopkins. He said there may be immune system elements other than the helper T-cells, however, that are responsible for suppressing HIV infection in the rare patients who never get sick from the virus.
In any case, Schwartz said, the new research emphasizes the importance of early and aggressive anti-viral treatment against HIV.
Copyright 1997/The Associated Press. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Permissions Desk, The Associated Press, 50 Rockefeller Plaza, New York, NY 10020.
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