Health

Is Your Immune System Aging Faster Than You Are?

We often think of wrinkles, declining energy, and increasing aches and pains as the telltale signs of an aging body. But it turns out that these common physical changes are only half the story of how we age.

It turns out that our immune systems — that brigade of special cells that fight off foreign invaders — can show definite signs of wear and tear as the years march on. What’s more, our immune systems can even age at a different rate — either faster or more slowly — from our chronological age.

But as UAB medical researchers are finding, having a “young” immune system seems to be one of the keys to living a long, healthy life.

The Effects of Aging on Our Immune Systems

“As people age, their immune systems often don’t function as well they did when they were younger,” says John D. Mountz, M.D., professor of medicine in the UAB Department of Immunology and Rheumatology and researcher in the UAB Center for Aging. “The human immune system has three main types of cells — microphages, T cells, and B cells. The T cells are the main problem in older adults.”

As Dr. Mountz explains, it’s a specific type of T cell — called CD8 — that deteriorates the fastest with age. “These immune cells have an important role within the immune system, so a decline in function can make people much more susceptible to infections and other illnesses,” Dr. Mountz adds. “For example, CD8 cells help to protect the body against the flu virus as well as cancer. Also, shingles — which many older people develop in response to the chicken pox virus — is an indicator of poor CD8 function. Many vascular and inflammatory diseases also develop because of low-functioning CD8 cells.”

Dr. Mountz adds that in general, the best advice for keeping your immune system strong and vital is to get plenty of good quality sleep, eat a nutritious diet, and get moderate amounts of exercise. “All of the major hormones in the body decline as we age, including thyroid hormone, growth hormone, estrogen, and testosterone. But we know that moderate exercise increases all of the body’s hormone levels and has a beneficial effect on controlling body weight – both of which are important for good immune function.”

UAB Study Sheds Light on Immune System Aging

A recent medical study conducted by Dr. Mountz and his colleagues at UAB reveals some interesting new findings about aging and the immune system. The study — conducted in collaboration with several other prestigious research institutions, including Tulane University — examined the functioning of CD8 T cells among three main age groups of people: young; middle aged (60-89); and older (90+).

The study found that people can have three immunological phenotypes, or levels of immune function: non-senescent (normal); pre-senescent; and senescent (indicating an aging immune system with diminished function). “In the test we performed as part of the study, we were able to distinguish an old CD8 T cell from a young CD8 T cell,” explains Dr. Mountz. “So the results indicated the immunological age of the person – which doesn’t necessarily correlate with the person’s chronological age.”

In fact, the study found that people of the same chronological age can have different immune phenotypes, or levels of immune aging. “Some people may have a high chronological age — such as those in the 90+ age group in our study — but they have a normal, or non-senescent, phenotype. This means that their immune system is functioning like that of a much younger person,” Dr. Mountz observes. “However, other people in the 90+ age group in our study had the senescent phenotype, indicating an aging immune system with compromised function.”

The study also found that, in general, the senescent phenotype (indicating an aging, lower-functioning immune system) was associated with an increased history of cancer in both the old and 90+ age groups. “Overall, the study results suggest that survival to age 90 or greater is associated with a slow progression of immune system aging,” explains Dr. Mountz. “Our future research will look at how these markers of immune function might change among the three age groups in response to certain factors, such as exercise.”