A new research by the Yale University suggests that aging impairs the immune response to flu in multiple ways. It mainly weakened resistance in older adults. Thus, they tend to have increased risk of illness and death from flu.
Scientists investigated the innate, or inborn, immune response to the flu virus. For this, they collected blood samples from healthy young adults and older adults aged 65 and above. They isolated monocytes, a type of white blood cell, from the samples and stimulated the monocytes with either flu virus or a mimic of the virus.
The immune response in cells from older adults was severely impaired in critical ways, the researchers found. To fight the flu virus, the body needs to activate potent antiviral proteins called interferons. But in older adults, this response is weakened by age-related damage to a molecule, TRAF3, that signals immune cells to make interferon. Without that signal, and another involving antiviral gene, resistance to flu falls short.
Senior author Akiko Iwasaki said, “Influenza virus mortality is the highest in older adults. This study sheds light on a mechanism that underlies this impaired antiviral response.”
“The finding offers new insight into why flu disease is severe in older adults. It also points to a potential strategy for reducing flu-related mortality in that age group.”
“In older adults, we might have to use a different strategy to treat and immunize against flu. We need to find a way to boost an 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.”