Fat sea fish like sardines are suppliers of vitamin D.
Reading aloud Vitamin D is surprisingly absolutely indispensable for the immune system: only if it is available in sufficient quantity, the killer cells of the body's defense are mobilized, so that they can fight invading viruses or bacteria. This is the finding of a Danish research team following a study of blood samples donated to five dialysis patients. Although it was already known that vitamin D can affect the immune system. However, how fundamental its function is has so far been overlooked, reports Carsten Geisler from the University of Copenhagen and his colleagues. Vitamin D is mainly produced in the skin when it comes into contact with the UV rays of sunlight, but is also found in various foods such as fish oil or eggs. The best known is because of its function in the calcium metabolism of the body as well as the bone structure. In addition, it has also been associated with autoimmune diseases such as multiple sclerosis and infections, such as tuberculosis. Only now, however, could Geisler and his team show how this influence on the immune system is likely to come about: The vitamin tears the killer cells of the body's defense, the T cells, from a sleep-like state and activates them, so that they attack targeted pathogens can.

Thus, this activation proceeds as follows: If a naive T cell, that is, a non-combatant T cell, comes into contact with a potential intruder, such as a fraction of a bacterial cell, it begins to produce a vitamin D recognition protein. This is then extended like a kind of antenna and tests if vitamin D is available. If the antenna registers the vitamin, an entire reaction cascade occurs. In the end, the T cell replicates, forming hundreds of identical cells, all focused on the spotted pathogen. If vitamin D is missing, however, this mobilization does not take place.

The results give previously unknown insights into the work of the immune system, the researchers emphasize. So you can help regulate the body's response in the future? not only in controlling infections, but also in suppressing excessive immune responses, such as those found in autoimmune diseases or rejection following organ transplantation. In both cases, activated T cells multiply explosively and produce inflammation that can have disastrous consequences for the body. By the way, in mice, the popular laboratory model, is there not a connection between vitamin D and T cells? presumably because the nocturnal hairy mice do not have much vitamin D available anyway, so it would not have been beneficial if this substance played such an important role in their immune system.

Carsten Geisler (University of Copenhagen) et al .: Nature Immunology, online pre-publication, doi: 10.1038 / ni.1851 ddp / science.de? Ilka Lehnen-Beyel advertisement

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