Researchers at UT Southwestern Medical Center identified a new source of neutrophils for production of an immunity protein interferon-gamma (IFN-γ) in the earliest response to infection. IFN-γ prevents a virus from replicating and also stimulates the immune system to produce other disease-fighting agents. Neutrophils are the major component of pus.
The new report reveals that neutrophils help produce IFN-γ through a new cellular pathway, which is independent of the pathway through Toll-like receptors (TLRs) as the body’s early warning system against invasion by pathogens.
“We believe our mouse study provides strong evidence that neutrophils, white blood cells created in the bone marrow, produce significant amounts of IFN-γ in response to disease,” said Dr. Felix Yarovinsky, assistant professor of immunology and senior author of the study published online in the Proceedings of the National Academy of Sciences in June. “The finding of a new and essential cellular source for IFN-γ challenges a long-held belief in the field and is significant because neutrophils are the most common kind of white blood cell.”
In this study, two pathogens were used: Toxoplasma gondii, which causes brain damage in mammals, and Salmonella typhomun, which causes gastroenterit. Innate immunity is the body’s first line of defense against pathogens, including those that have never before encountered, while Adaptive immunity is the secondary system to develop antibodies against pathogens which the body has previously been exposed to. It was believed for a long time that natural killer (NK) cells and T cells are the significant sources of IFN-γ, and the hypothesis that neutrophils also help production of IFN- γ as innate immunity process was ignored for 20 years up to now until Dr. Yarovinsky have identified this new source.
The researchers began the study about the possibility of neutrophils aiding production of IFN-γ because they found NK and T cell-lacking mice still managed to make IFN-γ using the other source. “Based on what we know about neutrophils, their large numbers and rapid deployment to the site of infection should provide an important means of very early, robust, and rapid elimination of disease-causing agents,” researchers wrote.
“Based on what we know about neutrophils, their large numbers and rapid deployment to the site of infection should provide an important means of very early, robust, and rapid elimination of disease-causing agents,” the researchers wrote. Although neutrophil-derived IFN-γ alone is insufficient to achieve complete host protection, the protein significantly extended the survival of mice in this study, Dr. Yarovinsky said.