Focus on the Flu : Older Adults

by National Institute of Health

(Page 2 of 15)

Can Older Adults Bulk Up Their Flu Abs (Antibodies) with Exercise?

The many benefits of an invigorating swim or brisk-paced walk have long been extolled by health care professionals. Now researcher Marian Kohut, Ph.D., assistant professor at Iowa State University in exercise physiology, may have found another virtue: exercise could help older adults fight off the flu. Dr. Kohut is leading a multidisciplinary team to determine whether or not exercise affects how well an older adult's immune system responds to a flu vaccine.

Each year, the flu can take a toll on seniors. People sixty and older don't get the same "oomph" out of a flu vaccine that a younger person does, and the incidence and severity of infection is much greater in the older population.

In an earlier study involving adults ages 62 and older, Dr. Kohut and researchers found that, among other things, adults who exercised regularly and vigorously produced higher levels of anti-influenza IgG and IgM antibodies (key influenza fighters) following flu immunization than those who exercised moderately or who were inactive.

Now, in an NIAID-sponsored study, the researchers are digging a little deeper. For one year, the team is comparing the immune responses of approximately 100 adults, all of whom were vaccinated against the flu and who are engaged in one of two exercise programs. Adults in group one exercise strenuously several times each week, while adults in group two take part in low-impact stretching exercises several times each week. In addition to measuring the production of anti-influenza antibodies such as IgG and IgG1, the researchers are looking at the number and activity of killer T cells, the immune cells that help rid the body of virus-infected cells, as well as other important immune system players.

Besides understanding if exercise improves immunity, the researchers are trying to understand why this might be the case. To do this, they are studying the psychosocial effects of exercise, monitoring such intangibles as stress levels and sense of purpose, to determine if the effects are due to psychological improvements. To help determine if neuroendocrine factors released during exercise, such as adrenaline and noradrenaline, may play a role in enhancing the immune response, researchers are testing the effects of exercise on people who take beta blockers, drugs that block the release of adrenaline to help slow the heart rate and lower blood pressure.

"If these chemicals do mediate the effects of exercise on the immune response, we would expect the changes in immunity due to exercise to be different in this group of subjects," says Dr. Kohut.

Older Adults and the Flu: How to Make the Most of a Flu Shot

Each flu season, a large segment of older adults will become seriously ill with the flu-flu shot or not. How come?

"As a person ages, her immune system will gradually weaken," says Yuping Deng, Ph.D., assistant professor of internal medicine at Eastern Virginia Medical School, Norfolk. Why this decline occurs is not entirely understood, but one theory is that the cells of the immune system that cause B cells to secrete protective antibodies-known as type 1 helper T cells (Th1 cells)-don't function as well in older people as they do in younger people. As a result, older adults produce fewer antibodies in response to a flu shot than will a younger person.

Earlier, Dr. Deng had found a potential relationship between Th1 cell function and the generation of antibodies in older people. Now, in a two-year study sponsored by NIAID, she is trying to understand the process a little better-and then give it a little nudge.

In 2004, Dr. Deng's team vaccinated healthy older adults and young people against the flu. Then the researchers monitored the activity of each group's Th1 cells by measuring how much interferon-gamma they secrete. Interferon-gamma is a chemical that causes B cells to produce flu-fighting antibodies, especially IgG1. The investigators then compared Th1 activity to antibody levels to see if the two factors are directly linked.

"We predicted that we would see a decline in Th1 cell activity in healthy older individuals. Our prediction was accurate; compared to the healthy young volunteers, older people in our study had a diminished Th1 response to vaccination," says Dr. Deng.

In the 2005-06 flu season, the researchers are conducting Phase I clinical trials to test whether either of two vaccination strategies can improve the immune response to flu vaccine in both healthy older adults and young people. In one strategy, Dr. Deng and her colleagues will follow up the usual flu vaccine with an injection of a molecule found in bacteria that helps stimulate the Th1 response. In the second strategy, they will administer a booster vaccine when Th1 cells are at their peak (7 days after vaccination), or when Th1 cell activity dies down (28 days after vaccination), to determine if immunity is enhanced.

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.