Their findings could provide researchers with a way to clamp down on dozens of autoimmune conditions caused by an overzealous immune system, such as Crohn's disease, lupus or even sepsis. Their research is the cover article for the November issue of the journal Immunity.
"When the immune system is activated there is a cascade of cytokine interactions that regulate the growth and functions of an array of immune cells," said Christopher Hunter, an associate professor in Penn's Department of Pathobiology and senior author of the paper. "Contrary to previous studies, the IL-27 cytokine actually limits the duration and intensity of T-cell activation, an 'off switch' as it were."
To gauge the function of IL-27, Hunter and his colleagues used mice that lack the cytokine's receptor, a protein called WSX-1. Without WSX-1, IL-27 lacked a target a button to press and the researchers were able to determine how the immune system worked without this particular cytokine.
When the animal models were challenged with a toxoplasma infection, their immune systems were able to fight off the parasite but their immune response continued well after the parasites were controlled. Instead, the researchers found a surplus of activated T cells and increasing amounts of interferon gamma, a cytokine that activates antigen-presenting cells and other parts of the immune system.
These results differed from previous studies that showed IL-27 to be among the many cytokines involved in T-cell differentiation and growth. Despite its simila
Contact: Greg Lester
University of Pennsylvania