Immune System Memory Linked to Interferon Alpha Activity

Immunologists have found that the ability of the human immune system to "remember” battling a specific pathogen requires the action of the cytokine, interferon alpha.

Investigators at the University of Texas Southwestern Medical Center (Dallas, USA; www.utsouthwestern.edu) sought to trace the molecular mechanism that enables a small cadre of immune T cells to "remember” the structure of viruses and bacteria that have been attacked and eliminated by the immune system. Of primary interest was the role of interferon alpha, a cytokine secreted by immune cells shortly after infection.

They reported in the December 15, 2008, issue of the Journal of Immunology, that the effects of interferon alpha were linked to the activities of two other molecules, the interleukins IL-2 and IL-12. After infection by an unknown pathogen, immune cells begin to secrete IL-12, which triggers the immune response and alerts other types of immune cells to attack the invaders. At the same time, IL-12 inhibits the activity of IL-2, which is required for immune cells to "remember” the identity of the pathogen. Now, interferon alpha enters the picture. Interferon and IL-12 work together to generate a special subset of cells that secrete IL-2. It is these IL-2-secreting cells that remain in the body and "remember” how to fight off the invader.

"Without the IL-2 signaling protein, you will generate a beautiful primary response against a virus, and you will eliminate the bug, but your body will not remember how it defeated the virus,” explained senior author Dr. David Farrar, assistant professor of immunology at the University of Texas Southwestern Medical Center. "Without these memory cells, your body is defenseless against reinfections.”

In this study, we have uncovered interferon's role and the key signaling protein, called IL-2, involved in generating memory T cells,” said Dr. Farrar. "Knowing how T cells acquire this memory may help us design better strategies and vaccines to fight HIV and other infectious diseases.

Related Links:
University of Texas Southwestern Medical Center