(ORDO NEWS) — A common cold many years ago can be beneficial if the body is fighting the new coronavirus.
Some people who have never had the new coronavirus may still have T cells that respond to it, according to a study . Scientists believe this is due to the fact that these cells have previously learned to identify and fight coronaviruses that cause the common cold.
A type of white blood cell, T cells are an important part of the body’s defense against the virus: they identify and destroy infected cells, and they also inform B cells how to make new antibodies. When you are infected, your immune system makes both antibodies and white blood cells.
Antibody levels can drop within months of infection, but T cells retain their “memory” for years and can help orchestrate a new attack if the same virus ever returns.
Recent research suggests that T cells that remember how to fight other coronaviruses can give people an immunological head start against the new coronavirus.
“This may help explain why some people show milder symptoms of the disease while others become more severely ill,” Alessandro Sette, co-author of the new study, said in a press release. However, he cautioned that it is too early to say whether this pre-existing immunological memory affects the course of the disease in COVID-19 patients.
Sette’s team analyzed blood samples collected between 2015 and 2018 from 25 people who, of course, have never had COVID-19. They found that these unirradiated people had T cells that could recognize both the new coronavirus and four types of other coronaviruses.
The Nature study also examined 23 survivors of SARS, which is also a coronavirus, and found that they still have SARS-specific T cells 17 years after their illness. These same T cells can recognize the new coronavirus.
The most likely explanation for these observations is a phenomenon called cross-reactivity: when T cells that develop in response to a single virus respond to a similar but previously unknown pathogen.
This can give the immune system support.
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