Washington: 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
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 dioxygenase, or IDO, to
turn off T cells. IDO is an enzyme used by fetuses and tumors
alike to escape the immune response, say the scientists.