COLUMBUS, Ohio Elderly people might not benefit from some of the tuberculosis vaccines currently in development, recent research suggests.
Some vaccines under study are designed to activate a specific molecule that is an early participant in the immune response against TB in young people. But a recent Ohio State University study suggests that in older people, this molecule remains relatively inactive, even in the face of TB infection.
The animal research suggests that the presence of this molecule, called a toll-like receptor, is not required in an old mouse to generate an immune response to Mycobacterium tuberculosis, the pathogen that causes TB infection. The immune response in young mice without the receptor, however, is not robust enough to adequately fight TB infection.
So while young people would stand to benefit from a vaccine that boosts this molecule's function, it appears a new direction in vaccine research is needed to ensure that the elderly also receive protection against the disease, researchers say.
One caveat, says Joanne Turner, associate professor of internal medicine at Ohio State and lead author of the paper, is that this finding occurred in mice that are completely lacking the receptor in question.
"If old mice have this receptor on the surface of their cells, it probably functions, but not as well as it should, and not as well as it does when mice are younger," Turner said. "When we take it away, something else works on its behalf. Our next step will be to find which receptor is responsible in old mice for sending the immune response signals, because that should be the focus of a vaccine for the elderly."
The study is published in a recent issue of the journal Mechanisms of Aging and Development.
About 2 billion people worldwide are thought to be infected with Mycobacterium tuberculosis. People can harbor the bacterium without symptoms for decade
|Contact: Joanne Turner|
Ohio State University