Natural Immune-System Molecule Helps Shield Against HIV

IL-7 could be useful complement to standard therapy, study suggests.

By E.J. Mundell
HealthDay Reporter
Tuesday, February 6, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

TUESDAY, Feb. 6 (HealthDay News) -- U.S. AIDS researchers are getting a better understanding of how an immune system molecule called interleukin-7 keeps cells from dying, even when they're under attack from HIV.

Clinical trials are already under way in which scientists are boosting HIV-positive patients' IL-7 levels to improve their immune health.

"We desperately need some way of protecting cells from dying in AIDS," said Rowena Johnston, vice president of research at the Foundation for AIDS Research (amfAR) in New York City.

While IL-7 therapy would never replace current highly active antiretroviral therapy (HAART) for patients, it might help repair the lasting damage that HIV inflicts on the immune system, she said.

"Because, even in the first few weeks of infection -- before you even know that you have HIV and haven't started therapy yet -- there is this lasting damage to the immune system that HIV does," Johnston noted. "That is something that absolutely needs to be addressed."

Johnston was not involved in the study, which was conducted by a team at the U.S. National Institute of Allergy and Infectious Diseases (NIAID). The researchers published their findings in this week's Proceedings of the National Academy of Sciences.

IL-7 is one of a number of interleukin molecules that the body uses as "long-range messengers" to recruit an immune response to sites of injury in the body, explained lead researcher Paolo Lusso. He is an adjunct investigator in the Laboratory of Immunoregulation at NIAID.

According to Lusso, IL-7, especially, is "recognized to be key to the well-being of the T-cell." T-cells are a type of immune system killer cell, as well as a regulatory cell.

A major subset of T-cells, called CD4-positive T-cells, are also the prime target of HIV. As the virus enters and kills these cells, it slowly destroys the human immune system, leaving AIDS patients vulnerable to deadly infections.

But "IL-7 helps keep T-cells alive," Lusso said. "When you get any knocks or damage that lowers the number of [T-cell] lymphocytes, IL-7 turns on to try and rebalance the situation."