THURSDAY, SEPTEMBER 29, 2016

Human immune system’s unique method of fighting TB

Human immune system’s unique method of fighting TB | Courtesy of bio.davidson.edu
A novel tissue culture model illustrates how a body with a latent tuberculosis (TB) infection does not contract active TB because its immune system takes a vital preventative step.

"This model using human cells provides evidence that there is an immune response generated during latency that reduces Mycobacterium tuberculosis growth and thus is host protective," Larry Schlesinger, senior author of the study and chair and professor of microbial infection and immunity at The Ohio State University, said. "At the same time, we can see that bacteria are adapting early in this environment, suggesting that at least a subset can develop into what we call persisters. These persisters are the bacteria that would have the potential to reactivate later to cause active disease."

The model, which contained human white blood cells, also showed that certain TB bacteria can detect alternate ways to infect the body without being blocked by the immune protection.

These model illustrations have helped health professionals understand how and why latent infections do or do not become active, transmissible TB.

The model immune cells surrounded the Mycobacterium TB cells to make a granuloma, which keeps TB latent. The latent-infected patients have immune systems that better defend their bodies against TB because their immune systems have already taken a first step toward preventing a full-blown case of active TB.

Experts estimate that over 2 billion people around the world have TB infections. They also estimate that there were 1.3 million deaths related to TB in 2012 alone.

"Many people in the U.S. think of TB as a distant disease that doesn't pose much of a threat,” Schlesinger said. “But the recent discovery of latent infections in Kansas schoolchildren who had contact with a single actively ill patient shows how widespread infection can occur with minimal exposure. This research might help us better predict what puts people with latent infection at higher risk of later developing active disease."

When people have latent TB infections, they can carry the diseases for decades before they experience any symptoms. Approximately one out of every 10 people with latent TB will develop the active from of TB.

The most common TB symptoms are chest pain and chronic coughing.




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