NEW YORK (Reuters) -- Government scientists say infusions of the immune system protein interleukin-2 (IL-2) helps to dramatically increase the disease-fighting capabilities of people infected with HIV.
Their study published in this week's issue of The New England Journal of Medicine found sustained increases in the primary immune system cell type called CD4+, the main target of the AIDS virus, following treatment with IL-2 and antiviral drugs.
The researchers say patients treated only with standard drugs against HIV showed decreased production of these crucial cells.
"Our study has clearly demonstrated that IL-2 therapy can have a substantial positive impact on the major immunologic abnormality associated with HIV infection, the loss of CD4+ T cells, without leading to an overall increase in the level of HIV in the bloodstream or to unmanageable toxicities," said study lead author Dr. Joseph Kovacs, senior investigator at the National Institutes of Health (NIH) Clinical Center, Bethesda, Maryland.
Kovacs is referring to previous studies showing that IL-2 treatment can result in occasional bursts of virus production in some HIV patients. The current study clearly indicates that these bursts do not lead to sustained increases in the viral load, or the amount of virus circulating in the patient's bloodstream.
This comes as welcome news for Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. Fauci supports AIDS treatments based on boosting a patient's immunities.
"This work highlights the potential role of immune-based therapies in the treatment of HIV-infected people," he said.
However, the accent remains on "potential." The study of 60 patients demonstrated that IL-2 can safely boost immune cell production from 428 cells per cubic millimeter of blood to 916 cells per cubic millimeter despite the onslaught of HIV. But, yet to be determined is whether these increases in CD4+ T cells will translate to fewer AIDS-related complications and improved survival for people with HIV.
"We look forward to a trial that will clarify the long-term clinical benefits associated with IL-2-induced increases in CD4+ T cells," said Dr. David Cooper, director of Australia's National Centre in HIV Epidemiology and Clinical Research in Sydney. Cooper has studied IL-2 and works closely with NIH investigators in developing a clinical study of IL-2 therapy in AIDS patients with CD4+ cell counts above 400.
So far, an extended phase of the current study showed that increases in CD4+ cells could be sustained for more than two years by continuing to administer IL-2 on an individualized schedule. In five patients, cell counts remained over 1,000 for at least 18 months after discontinuing IL-2.
"To date, no combination of anti-retroviral agents has been shown capable of inducing increases in CD4+ T cell counts of this magnitude or duration," the authors state.
SOURCE: The New England Journal of Medicine (1996;335(18):1350-1356)
