The same trait that makes a rare immune cell invaluable in fighting some infections also can be exploited by other diseases to cause harm, two new studies show.
In papers published online in Immunity, scientists at Washington University School of Medicine in St. Louis reveal that the cells, known as CD8 alpha+ dendritic cells (CD8a+ DCs), can help the body beat back infection by a common parasite, but the same cells can be hijacked by a bacterium to decimate the body’s defenses.
The trait that makes the cells both an asset and a liability is the way they alert other immune cells, causing them to attack invaders. CD8a+ DCs can sound the alarm in a manner that is particularly helpful for stripping away invaders’ disguises. But this process takes time, and Listeria
bacteria can take advantage of that delay to wreak havoc inside the spleen.
“As we’ve discovered how useful these cells can be in fighting different kinds of infections, researchers have wondered why they’re so rare,” says Kenneth Murphy
, MD, PhD, the Eugene L. Opie First Centennial Professor of Pathology and Immunology. “This may be why — overcommitting to any one defensive strategy opens up opportunities for counterstrategies that exploit it.”