Growth hormone may help to stave off AIDS, research shows.

In a new study, growth hormone injections stimulated the production of immune system cells that can help the body fight infection, says Kimberly Smith, MD, MPH, associate professor of medicine at Rush University Medical Center in Chicago.

The researchers looked at immune cells known as CD4 T cells, which are destroyed by HIV. As the number of disease-fighting CD4 cells drops, HIV-infected persons lose their ability to fight off infections related to AIDS.

Smith's study, presented here Tuesday at a meeting of the International AIDS Society, included 54 HIV-infected persons who had poor immune system function despite treatment with standard AIDS medications.

"Antiviral drugs controlled the amount of virus in their blood, but these people still had an inadequate immune response with a low CD4 cell count," Smith tells WebMD.

Smith added growth hormone to their treatment plan after animal studies showed that it boosts thymus function, which is involved in production of CD4 cells.

About half the people got growth hormone injections plus their usual HIV medications for 48 weeks. The others continued their HIV drugs alone for 24 weeks followed by growth hormone injections for another 24 weeks.

Growth hormone treatment increased average CD4 cell counts by 15 percent to 20 percent by the end of the study, she says.

More importantly, growth hormone was associated with a 50 percent to 60 percent rise in so-called naive CD4 cells -- a specific type of CD4 cell "that is important for fighting viruses that the body never saw before," Smith says.

Side effects of the treatment, while infrequent, included body aches and liver enzyme abnormalities.

Growth hormone is typically prescribed for children whose pituitary glands do not make amounts of the hormone sufficient for normal growth.

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Hope for Restoring Embattled Immune Systems

While the study offers hope that growth hormone can stimulate the thymus to produce CD4 cells and help restore ravaged immune systems in HIV-infected people, it's way too soon to recommend the treatment, Smith says.

First, larger numbers of people need to be followed for longer periods of time to see if growth hormone actually keeps AIDS-related infections at bay, she says.

Albert Duarte, MD, PhD, associate professor of medicine at the University of Sao Paulo in Brazil and moderator of the session at which the findings were announced, says that while the results are promising, he thinks that growth hormone is too costly to use as an anti-AIDS medication.

But if the findings pan out in future studies, they could pave the way to the development of an immune-boosting vaccine to treat people with HIV infection, Duarte says.

"Stimulating the thymus to produce T cells may be a viable vaccine strategy," he tells WebMD. "But because growth hormone is very expensive, there's no room for it now."

Smith acknowledges the high price tag, although she points out that people in the study got a much lower dose than is typically prescribed to children with growth hormone deficiency. She estimates that the cost of treating a child with growth hormone deficiency is about $5,000 a year.

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By Charlene Laino, reviewed by Michael W. Smith, MD

SOURCES: 3rd IAS Conference on HIV Pathogenesis and Treatment, Rio de Janeiro, Brazil, July 24-27, 2005. Kimberly Smith, MD, MPH, associate professor of medicine, Rush University Medical Center, Chicago. Albert Duarte, MD, PhD, associate professor of medicine, University of Sao Paulo, Brazil.