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.
The study adds to an ever growing body of science supporting the benefits of maintaining healthy vitamin D levels.
In adults, it is said vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases. There is also some evidence that the vitamin may reduce the incidence of several types of cancer and type-1 diabetes.
According to the Copenhagen-based researchers, activated T cells can become one of two types of immune cell: 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 cell is not activated it is known as a naïve cell.
For their research, researchers led by Professor Carsten 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.”
The findings could help us combat infectious diseases and global epidemics, said Prof Geisler. Indeed, last year the Public Health Agency of Canada (PHAC) confirmed that it will be investigating the role of vitamin D in protection against swine flu.
Source: Nature Immunology
Published online ahead of print, doi: 10.1038/ni.1851
“Vitamin D controls T cell antigen receptor signaling and activation of human T cells
Authors: M.R. von Essen, M. Kongsbak, P. Schjerling, K. Olgaard, N. Odum, C. Geisler