Vitamin D critical in activating first-line immune defence
Copenhagen – Danish Scientists have established that activation of the first-line defence of our immune system depends on Vitamin D, and that without sufficient intake of the vitamin, T cells (killer cells) cannot react to and fight off serious infections in the body. For T cells to detect and kill foreign pathogens such as bacteria or viruses, the cells must first be triggered into action, transforming from inactive, naive, immune cells into the killer cells that seek out and destroy all traces of a foreign pathogen. A team headed by Professor Carsten Geisler from the University of Copenhagen deciphered the complex signalling pathway crucial for such priming of the immune cells (Nature Immunology). They established that triggering of naive immune cells boosted expression of Phospholipase C-gamma1, a key signaling protein that regulates responsiveness of T cell antigen receptors (TCR), which switch on antigen-dependent maturation of naive T cells to fully active T killer cells. However, in the absence of Vitamin D, Phospholipase C-gamma1 levels and concentration of the Vitamin D receptor remained low in naive T- cells and they remained in dormant stage. Activation of Phospholipase C-gamma1 expression seemed to require a signal mediated by the Vitamin D-receptor. The research team said, identifying the role of vitamin D in the activation of T cells was a major breakthrough. The discovery will help them regulate the immune response, for example after organ transplantation, in autoimmune or infectious diseases, where overshooting immune responses can become dangerous for the patients.