The surprising downside of youthful immunity in seniors

Staying young might not be all it’s cracked up to be.

While most people experience a decline in immune function with age, new research has found that a fortunate few maintain a powerful defense thanks to rare immune cells that stay active well into their senior years.

But this “fountain of youth” effect comes at a cost. The same immune strength that helps ward off infections may also increase the risk of serious diseases like lupus, rheumatoid arthritis and ulcerative colitis.

Mayo Clinic researchers discovered cells linked to what they call “immune youth” while analyzing data from more than 100 older patients being treated for giant cell arteritis.

This autoimmune disease causes inflammation and narrowing of arteries — especially those in the head and neck — restricting blood flow and potentially leading to significant complications if left untreated, like vision loss.

In the affected tissue of these patients, the team found specialized immune cells called stem-like T cells.

Usually, these cells function like young stem cells that support healing and growth, but in this instance, they were fueling the spread of the disease.

“We observed that these patients have very young immune systems despite being in their 60s and 70s. But the price they pay for that is autoimmunity,” Dr. Cornelia Weyand, a rheumatologist and lead author of the study, said in a statement.

Autoimmunity occurs when the body’s immune system mistakenly attacks its own healthy tissues and organs. This can lead to a range of autoimmune diseases, with symptoms varying from mild and manageable to severe and debilitating.

The researchers also found that immune checkpoint inhibitors — proteins that act as “brakes” on the immune system — were not functioning properly in the giant cell arteritis patients with stem-like T cells.

“Contrary to what one may think, there are benefits to having an immune system that ages in tandem with the body,” said Dr. Jörg Goronzy, a Mayo Clinic aging researcher and co-lead author of the study.

“We need to consider the price to pay for immune youthfulness,” he continued. “That price can be autoimmune disease.”

Across the country, an estimated 50 million Americans — about 15% of the population — live with autoimmune diseases, and research indicates these numbers are increasing.

Some of the most common autoimmune disorders include Crohn’s disease, type 1 diabetes, multiple sclerosis, Hashimoto’s thyroiditis, celiac disease and psoriasis. Conditions like giant cell arteritis and Sjögren’s syndrome, which attacks the body’s moisture-producing glands, are especially prevalent among older adults.

“We want to learn from them,” Weyand said, referring to those with a “fountain of youth” in their immune systems.

Building on this discovery, the researchers are developing new diagnostic tests to identify patients — and even healthy people — who carry high levels of immune stem cells and may be at greater risk of developing autoimmune diseases later in life.

Timely identification is crucial because patient outcomes can be significantly improved with early intervention, helping to prevent or slow disease progression, reduce long-term complications, and enhance quality of life.