Older patients' immune systems stronger than expected, McMaster study finds

A discovery by a McMaster researcher may lead to more effective vaccines for people of all ages.
Jonathan Bramson, the study's lead investigator, said the results were the opposite of what they expected. (Courtesy McMaster University)

Some aspects of immune function don’t deteriorate with age, according to a new study led by McMaster University researchers, and it could pave the way for more effective vaccinations.

It’s long been understood that the reason older people are more susceptible to infectious diseases is because of lowered immune function. While that is part of the story, it doesn’t paint a complete picture, as researchers have now learned.

In the study, T cells — a type of immune cell — were shown to respond to virus infections in older people just as effectively as in younger subjects.

The difference lies in the cells’ function. While antibodies (another type of immune cell) provide an initial defense against infections, T-cells hold the memory of previous infections and "remember" how to fight off disease, according to Jonathan Bramson, the study’s principal investigator.

"Antibodies are like a fence, but a T-cell is like a sniper fighting off infections," Bramson explained.

"While there may be something wrong with the fence in older people, the research shows that the sniper is still very much intact."

Bramson’s team studied individuals infected with West Nile virus through natural causes — the team didn’t inject anyone with the virus. They expected to see a difference in the way T-cells in older subjects functioned when encountering the virus compared to younger counterparts, but they saw no difference at all.

"In older people, the T-cell responses are completely intact," Bramson said. "They looked great."

The breakthrough could mean a change in the way vaccines are developed and to whom they are administered.

At the moment, many vaccines don’t focus on activating the T-cells, but instead activate the antibodies, Bramson explained. Since the antibodies are often weakened with age, it’s sometimes considered risky to administer these vaccines to elderly patients.

"But if we can create vaccines to activate T-cells, we can protect older patients from things like influenza. The flu vaccine is currently only moderately effective in older individuals," he said.

He said it could also make vaccines more effective for the wider population. Some research even suggests a T-cell-activating flu vaccine wouldn’t need to be altered every year like the current vaccine.

While the discovery wasn’t expected, Bramson was enthusiastic about the results and said the research could lead to further possibilities.

"I think this will cause people to change their attitude in what you can and can’t do with older individuals."