[ad_1]
Scientists have discovered a mysterious population of previously unknown cells lurking in the human body, according to a new study.
The new type of enigmatic cell, called immune cell X, is a changelin that can act as two other types of cells. And this rogue hybrid cell can trigger type 1 diabetes.
Scientists have long thought that such hybrid cells could not exist. The population of these cells is probably tiny; perhaps fewer than 7 in 10,000 white blood cells, said Abdel-Rahim A. Hamad, co-author of the study, associate professor of pathology at the Johns Hopkins University School of Medicine in Baltimore .
But they can play a disproportionate role in the development of autoimmunity.
"They are very rare, but we think they are very powerful," Hamad told Live Science.
Related, connected, related: 11 surprising facts about the immune system
Immune cascade
Normally, white blood cells patrol the body by swallowing foreign invaders such as bacteria or viruses. After digesting these invaders into tiny fragments, the white blood cell displays one of these digested fragments, or antigen, on the surface of its cell.
Two types of white blood cells – B and T lymphocytes – are incredibly powerful tools in the arsenal of the immune system. B cells generate billions of individualized antibodies, which bind only to specific antigens. Killer T cells destroy cells with specific antigens, and B and T cells can activate, creating a powerful feedback loop.
The key to all these processes is a special protein on the outer surface of immune cells called major histocompatibility complex (MHC), which is the host site for the antigen. B cells bind the antigen to MHC and T cell receptors then bind to this antigen-MHC complex and activate T cells.
In autoimmune diseases, this process is corrupt and the body's own cells are confused with foreign enemies. In type 1 diabetes, the immune system relentlessly destroys the beta cells of the pancreas that make insulin hormone. Without insulin, the body can not use the energy contained in food and a person will eventually die.
But what initially triggers this attack and how does it become impossible to stop? Previous work has suggested that the body in one way or another perceives the insulin molecule itself as foreign, which triggers type 1 diabetes and high risk individuals. often make slightly different versions of MHC proteins.
But it was a puzzle, because insulin Hamad explained that these high-risk versions of the MHC do not bind well, which means that it should theoretically not trigger a strong autoimmune attack.
Powerful immune trigger
In the new study published in the journal Cell, Hamad and his colleagues discovered a potential culprit. Using blood samples from healthy people and type 1 diabetes as well as computer simulations of B and T cells, the team discovered the existence of an "X cell" that has receptors of both B cells and T cells.
X-cell appears to be an extremely potent factor of autoimmunity. X-cells produced antibodies that strongly activated T cells in samples from people with high-risk MHC. This triggered the T cells that are ready to attack the beta cells of the pancreas to start dividing like crazy, Hamad said.
The team found evidence of these self-reactive X-cells in blood samples of people with type 1 diabetes, but not in healthy controls.
Not all history
The results are interesting, but can not be said because there are clear environmental triggers for type 1 diabetes, said Matthias von Herrath, director of the Institute for Immunology's Type 1 Diabetes Research Center. from La Jolla, not involved in the study.
In addition, "we do not know if there is a single cell responsible," von Herrath told Live Science.
To actually strengthen the case of X-cells, follow-up studies should try to find these unwanted hybrid cells in a specific body part related to the disease – like the pancreas or the lymph nodesadded von Herrath. Scientists would also like to know how many of them are hiding in the body, he said.
And there is another possibility: these X-cells look like both B-cells and T-cells because they are actually these two cells, and not at all a new type of ultra-powerful cell.
Scientists would like to verify that this X cell – which looks like a cell with two roles – is not actually two "cells in a close embrace," von Herrath said.
That said, the study was conducted carefully, with many tests to ensure that it was not the case, he said.
Even if the dishonest hybrid cell is not the entire history of type 1 diabetes, "even finding a cell of a certain type that would be the main culprit in some cases would be a significant step forward," said von Herrath.
Originally published on Science live.
[ad_2]
Source link