BREAK FROM HIV DRUGS BOOSTS BODY IMMUNE SYSTEM FIGHTS BACK AFTER
TIME OFF FROM TREATMENT
By Steve Sternberg
USA Today 27 Nov. '00
Experimental research with monkeys helps explain why three-week
holidays from anti-HIV drugs appear to bolster the immune system
and permit it to control the AIDS virus.
"This study represents the first evidence that treatment interruptions
make a difference, both in terms of the immune system and of viral
control," says Franco Lori of the Research Institute for Genetic
and Human Therapy in Washington, D.C.
Lori's team found that treatment interruptions arm key immune
system cells, called killer T cells, to attack and destroy HIV.
The process works this way: When HIV goes untreated, the virus
simply overwhelms the immune system. Hitting the virus hard with
drugs early in the infection safeguards the immune system. Alternating
treatment with drug holidays keeps virus levels low and permits
the immune system to attack HIV.
Lori and collaborator Julianna Lisziewicz have developed a test
of killer T cell function. The test, Lori says, "directly measures
the immune system's ability to control the virus."
The work reflects a trend in AIDS research -- finding cheaper,
simpler and more effective ways to treat AIDS using available
Lori, Lisziewicz, Bruce Walker at Massachusetts General Hospital
in Boston and Clifford Lane at the National Institute of Allergy
and Infectious Diseases (NIAID) in Bethesda, Md., among others,
hope to accomplish that goal by strengthening immunity.
Walker reported in September that treatment interruptions work
in a small number of humans, but the study didn't explain why
they work. "But it's very difficult to study the mechanisms in
humans," NIAID director Anthony Fauci says. "Tissue isn't easily
available, and it's tough to get people who are truly (newly)
Unless people are newly infected, their immune systems may be
too damaged to rebound after treatment.
The monkey study supports Walker's finding that treatment interruptions
help the immune system. "The monkeys show that very clearly,"
Lori says. "Every time there's a treatment interruption, the
immune system becomes stronger and stronger. Eventually, it is
able to control the virus without therapy."
The report, in the current issue of Science, involves three
groups of monkeys. One group of six monkeys was treated continuously
with antiviral drugs. Another group alternated between three weeks
on drug therapy and three weeks off. A third group received no
"The group that received continuous therapy did not mount any
immune response against the virus," Lori says. "The group that
received intermittent therapy had a very strong, virus-specific