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Scientists explore possible new way to fight AIDS

By Will DunhamTue Feb 6, 9:13 AM ET

A naturally occurring molecule saves vital immune system cells from
cellular suicide during the onslaught of the AIDS virus and might help
keep the body's natural defenses working in HIV-infected people, a
study found.

The findings represent a potential new avenue to fight the effects of
the human immunodeficiency virus, HIV, according to U.S. National
Institutes of Health scientists whose work was published on Monday in
the Proceedings of the National Academy of Sciences.

Dr. Paolo Lusso and colleagues at the NIH's National Institute of
Allergy and Infectious Diseases looked at the role played by
interleukin 7 in averting the death of T cells, a kind of white blood
cell important to the immune system.

Interleukin 7 is a substance important in maintaining proper
functioning of the immune system.

AIDS has killed more than 25 million people since it was first
recognized in 1981. About 40 million people now live with HIV, with
sub-Saharan Africa hardest hit.

Lusso expressed "reasonable optimism" that treatment involving
interleukin 7 may benefit people with AIDS, a disease for which no
cure exists.

"I don't think one solution will be applicable to all the patients.
It's possible that IL-7 (interleukin 7) may benefit some patients and
do nothing in other cases," Lusso said in an interview.

"But I think we are moving in the right direction because we are
starting to appreciate that antiretroviral therapy alone (existing
AIDS drug treatment) is not sufficient to bring back a full immune
competence, and we are starting to identify at least some strategies
that may work."

IMMUNE SYSTEM TARGETED

An insidious aspect of HIV is that the virus attacks the body's
natural defenses -- the immune system.

In assaulting the immune system, HIV hides inside certain T cells.
These cells, as the infection progresses, commit cellular suicide --
called apoptosis -- undermining the body's ability to combat
infections and certain cancers. In fact, the virus manages to induce
the suicide of many more T cells than it directly infects.

The researchers, who also included Dr. Lia Vassena and NIAID Director
Dr. Anthony Fauci, used blood samples from 24 HIV-infected people.
They added interleukin 7 to the blood samples and then gauged the
survival of T cells.

The actual patients themselves were not treated with interleukin 7.

The samples with interleukin 7 displayed lower levels of T cell death.
The benefits differed from sample to sample based on the person's
stage of infection, the study found.

The researchers believe interleukin 7 potentially could be used
alongside existing AIDS drugs to bolster the immune system.

Lusso noted that existing AIDS drugs can keep the virus at bay for
years, but damage to the immune system commonly persists even after
years of such treatment.

Scientists want to find new ways to remedy these immune defects, with
the aim to make the immune system functional even in HIV-infected people.

Lusso said apoptosis may be a major mechanism through which T cells
die in AIDS. The new study is important, he said, in that it
identifies how interleukin 7 may help -- by preventing these cellular
suicides.

He said the next step is a study in which monkeys with the simian
equivalent of HIV are given interleukin 7 to see if it blocks immune
system dysfunction and immune cell depletion.