A new type of dendritic cells
Scientists: immunity fights viruses with the help of "kamikaze" cells
Biologists have discovered an unusual type of immune cells whose main task is to get infected with the virus, die and spread information about it among other components of immunity, according to an article published in the journal Science Immunology (Silvin et al., Constitutional resistance to viral infection in human CD141+ dendritic cells).
"We found that there is a special subtype of dendritic cells into which viruses easily penetrate and which actively produce fragments of viral particles. Another type of dendritic cell picks up these fragments and uses them to train T cells to fight this virus. Such a "division of labor" explains how immunity works and why vaccines protect us from infections," says Karolina Palucka from the Baylor Institute in Dallas (in a press release Dendritic cells "divide and conquer" to elude viral infection while promoting immunity – VM).
The so-called dendritic cells are a kind of first line of defense of the body against bacterial and viral infections unfamiliar to it. They live on all mucous membranes and on the walls of blood vessels and are the first to come into contact with all pathogens that enter the body from the outside.
Their job is to "swallow" and study viral particles, followed by the transfer of critical information about them to T cells for the production of antibodies. At the same time, the main mystery of their existence, as Palutska notes, was how they do not die and do not get infected.
There is at least one type of virus – HIV, which is able to penetrate dendritic cells and use them to "travel" to other parts of the immune system or as a "bunker" to protect against antiretroviral drugs. For this reason, scientists are now actively studying how such cells work and looking for ways to control their work.
Palutska and her colleagues found out that the mechanism of these cells is actually extremely simple. Scientists have found that dendritic cells can be divided into two subgroups: ordinary and special "kamikaze cells".
The latter, as biologists have discovered, do not resist infection with the virus and contribute to its reproduction within themselves, actively releasing fragments of viral particles into the external environment. After a while, they die and fall apart, releasing both full-fledged and damaged viruses.
These fragments of viral shells and proteins are picked up by dendritic cells of the second type, which analyze them and transmit information about them to T cells, which, in turn, produce antibodies and cause the rest of the immune system to attack HIV or influenza.
Why do viruses attack "kamikaze", and not ordinary dendritic cells that pose a real threat to them? The fact is that in these cells there is a special protection system, the RAB15 protein, which does not allow the virus to "glue" itself with their shell and penetrate inside. Such a substance is absent inside the "kamikaze cells", due to which viruses penetrate them much more often and faster than in other dendritic cells.
The discovery of this system, scientists hope, will help us understand how retroviruses, including the immunodeficiency virus, "deceive" the immune system and spread through the body with impunity, and how this can be prevented.
Portal "Eternal youth" http://vechnayamolodost.ru
10.07.2017