Aging Weakens Immune Response to Influenza

The aging process may weaken the immune system’s ability to respond to the influenza virus in ways that leave elderly patients vulnerable to infection, according to a study published by Science Signaling.

These findings may explain why older patients are more likely to contract the flu and die from the infection, the authors suggest.

Health experts and organizations urge patients to receive the influenza vaccine each year to prevent infection and potential adverse events. Not receiving the vaccine can be especially dangerous for both young and elderly patients, as well as those with compromised immune systems.

“Influenza virus mortality is the highest in older adults. This study sheds light on a mechanism that underlies this impaired antiviral response,” said senior author Akiko Iwasaki, PhD.

The authors collected blood samples from healthy young adults and individuals 65 years and older to investigate the innate immune response to the flu. The researchers isolated monocytes—a type of white blood cell—and stimulated the cells with the flu or a mimic of the virus.

The study authors discovered that the immune cell response to the flu was significantly dampened in crucial ways among older patients, according to the study.

To combat the flu, the body activates interferons, which are antiviral proteins. In older adults, this response was observed to be diminshed due to age-related damage to the TRAF3 molecule, according to the study.

The authors said that TRAF3 signals the immune cells to produce interferon, and without the signal, the fight against the flu is ineffective.

These results may provide new insight as to why older adults develop more severe influenza infections. The authors note that this could become a potential treatment strategy to reduce flu-related mortality among older adults, but additional studies are needed.

“In older adults, we might have to use a different strategy to treat and immunize against flu,” Dr Iwasaki said. “We need to find a way to boost antiviral defense that does not rely on interferon production. For vaccines, we need to find an adjuvant — a component added to a vaccine — that would still stimulate the innate immune response in older adults.”