Researchers at Washington University School of Medicine in St. Louis say that immune cells that bacteria have exploited can be both helpful and harmful in fighting infection.
The cells could be particularly useful in efforts to turn the immune system against cancers using vaccines.
Scientists revealed 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 defences.
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," said 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," added Murphy.
CD8a+ DCs make up about 10 percent of all dendritic cells in the body. By studying the basic functions of these cells, scientists are laying the groundwork to use them to fight infections. The cells also appear to be essential for some cancer vaccines, which enlist the power of the immune system to help fight tumors.
The study has been detailed online in Immunity.