Vitamin D crucial for activating infection fighting T cells
The role of vitamin D for fighting infection has become clearer. Researchers now know that vitamin D is essential for activating immune defenses from T cells that otherwise lie dormant and allow bacteria to invade.
Recognizing the role of Vitamin D for immunity could improve outcomes for individuals who develop autoimmune diseases, face rejection from organ transplant, and could also lead to new ways to combat infectious diseases on a global scale.
Professor Carsten Geisler from the Department of International Health, Immunology and Microbiology at the University of Copenhagen where the research was conducted explains that "when a T cell is exposed to a foreign pathogen, it extends a signaling device or 'antenna' known as a vitamin D receptor, with which it searches for vitamin D. This means that the T cell must have vitamin D or activation of the cell will cease. If the T cells cannot find enough vitamin D in the blood, they won't even begin to mobilize. "
T cells that fight infection spring into action when macrophages that also play a role in immune function “tell” them a foreign substance or pathogen has invaded. T cells then attach to the invader, multiplying into hundreds of identical cells that sensitize the body to recognize future threats. T cells also destroy foreign cells, playing a dual role in immunity. But without sufficient vitamin D the immune system cannot become activated. The findings are considered a major breakthrough.
Dr. Geisler says the findings that vitamin D is absolutely necessary for immune function “will be of particular use when developing new vaccines, which work precisely on the basis of both training our immune systems to react and suppressing the body's natural defenses in situations where this is important.”
Taking 25 to 50 mcg of vitamin D daily is recommended by some experts, but no one has been able to establish what levels in the bloodstream are optimal. Study findings consistently show that vitamin D levels are deficient in large portions of the population.
Understanding the role of vitamin D in immunity can help researchers modulate the immune response by finding ways to turn inactive T cells into infection fighting killers. Without vitamin D immune fighting cells remain dormant.
Nature Immunology: doi:10.1038/ni.1851