(Reuters) – A lower supply of a certain type of immune cell in older people that is critical to fighting foreign invaders may help explain their vulnerability to severe COVID-19, scientists say. When germs enter the body, the initial “innate” immune response generates inflammation not specifically targeted at the bacteria or virus.
Within days, the more precise “adaptive” immune response starts generating antibodies against the invader along with T cells that either assist in antibody production or seek out and attack infected cells.
In a small study published on Wednesday in Cell, COVID-19 patients with milder disease had better adaptive immune responses, and in particular, stronger T-cell responses to the coronavirus.
People over age 65 were much more likely to have poor T cell responses, and a poorly coordinated immune response in general, coauthor Shane Crotty of the La Jolla Institute for Immunology said in a news release.
As we age, our supply of “naive” T cells shrinks, he explained. Put another way, we have fewer “inexperienced” T cells available to be activated to respond to a new invader. “Ageing and scarcity of naive T cells may be linked risk factors for failure to generate a coordinated adaptive immune response, resulting in increased susceptibility to severe COVID-19,” the researchers said.
