In what could be called a major breakthrough, scientists claim to have discovered a rare hybrid cell which is key to regulating the immune system.
A team at the Medical College of Georgia has found the cell -- a unique hybrid of two well-known immune cell types -- is small in number, but powerful in its ability to switch the immune system on or off.
“This is actually the first cell we know of that has this type of appearance in nature,” Dr. Andrew Mellor, who led the team, said.
According to the scientists, the discovery of this rare hybrid could have implications for the efficacy of new therapies that manipulate these two cell types to treat diseases such as cancer and rheumatoid arthritis.
They called this cell a subset of the dendritic cell that clusters in high exposure areas such as the gut but also roams the body, looking for invaders like a virus or even cancer.
Dendritic cells show their find to T cells, telling them to ignore or attack by bringing trash—eating macrophages, natural killer cells and the like into the fight.
What seemed most unique about the subset is its ability to express indoleamine 2,3 deoxygenise, or IDO, to turn off T cells. IDO is an enzyme used by fetuses and tumours alike to escape the immune response, say the scientists.
The new research shows that is only part of the cells’ distinctiveness. The cells also have the identifying markings of B cells, known for their ability to make antibodies against invaders.
In fact, they found the IDO—presenting cells came from the same precursor cell as B cells. But, when the scientists looked at mice missing B cells, they found the IDO—producing cells. Hence, the cell didn’t need to produce antibodies to turn off T cells.
“In reality, IDO—expressing cells have properties of both cells. It looks like a B cell and it’s not. It looks like a dendritic cell and it is and it isn’t,” co—scientist Burles A. Johnson said.
While their studies are in mice, the cells also are in humans, showing up in some unfortunate places such as the drainage system for tumours, melanoma or even HIV where they likely help the diseases survive.
“They also may be showing up in new dendritic cell therapies designed to strengthen the immune response to cancer. If the therapies happen to include some IDO—expressing cells, those could end up helping the cancer.
“All you need is a few of these cells in your dendritic cell vaccine and you don’t get stimulation any more, you get suppression,” Dr. Mellor said.