As people age, their bodies have a harder time fighting off infections, and in a recent study published in The Journal of Immunology, a local research team has found a key to understand why this happens.

New findings say that two separate defects combine to reduce T-cell responses as people age.

T-cells are part of the body's immune system and are important for defending off viruses, bacteria and other pathogens.

The immune system is highly connected - it has a lot of different cells that need to communicate to one another, and need to detect the viruses and bacteria as they infect the body, said Janko Nikolich-Žugich, co-director of the UA Center on Aging and chair of the UA Department of Immunobiology.

"(The immune system) is very precise and fine...like a machinery...and as we grow old, different facets of that process, all go awry a little bit, not in everybody, not all at the same time, but eventually as we grow older and older, many of these pieces don't communicate to one another very well, they don't detect the bugs very well, and one of the greatest challenges to immunologists is to understand how many defects there are and which defects are the most important," he said.

This research could help explain why the immune system is less able to respond to foreign invaders as someone ages, and understand why certain infections are, at times, more harmful to older people, he explained.

"...SARS showed up several years ago and was very deadly to older people...monkeypox showed up, also deadly to older people...West Nile virus very deadly to older people," Nikolich-Žugich explained. "All of these little defects can combine to result in a major vulnerability of the older population."

There are some people whose immune systems look very good and that might continue well into their 80s, but then there are people whose immune systems are not as good, "then the question is to understand where and how we can intervene to best to fix that immune system, and make sure these infections and diseases are not a problem for older adults," he said.

An important development from their research, and other studies happening around the world, would be the creation of medication that would rejuvenate the immune system, meaning it would help the body produce more T-cells, he said.

Nikolich-Žugich suggested it probably won't take more than 10 years until medication of such caliber is produced, and it would be especially beneficial to older adults who are more vulnerable than others in being unable to fight off infections, such as the flu.

Nikolich-Žugich said flu vaccines are less effective in people over 65. And, while oftentimes it is possible to give them a more powerful version of the vaccine, that doesn't always work. However, if there were medication that can rejuvenate the immune system, then these types of vaccines and treatments would work in a greater number of people, no matter what age.

"This is where rejuvenation comes into play...for those who have barely any protection against these viruses," he said.