Lee Swanson Research Update

Vitamin D May Play Key Role in Immune System Activation

April 2010

"The findings could help us combat infectious diseases and global epidemics," Professor Carsten Geisler said, referring to a new study that shows insufficient levels of vitamin D may reduce the immune system’s ability to react to infection. In fact, the Public Health Agency of Canada confirmed that it will be investigating the role of vitamin D in protection against swine flu.

Vitamin D is necessary to trigger T cells—the immune system’s killer cells—into action, and insufficient levels of the vitamin mean the cells remain dormant and inactive, according to findings published in Nature Immunology.

“Scientists have known for a long time that vitamin D is important for calcium absorption and the vitamin has also been implicated in diseases such as cancer and multiple sclerosis, but what we didn’t realize is how crucial vitamin D is for actually activating the immune system—which we know now," said scientists from the University of Copenhagen.

According to the researchers, activated T cells can become one of two types of immune cells: killer cells that attack and destroy all cells carrying traces of a foreign pathogen; or helper cells that assist the immune system in acquiring "memory." If the cells are not activated they are known as naïve cells.

For their research, scientists led by Prof. Geisler examined the expression of a specific molecule (PLC-gamma1) that would enable the cell to deliver an antigen-specific response. They found that naïve T cells had very low expression of PLC-gamma1 and that triggering of the T cell led to a 75-fold increase in PLC-gamma1 expression. Their data also showed that induction of PLC-gamma1 was dependent on vitamin D.

"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," explained Prof. Geisler. "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."

Nature Immunology Published online ahead of print.

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