WEDNESDAY, Jan. 27, 2021 (HealthDay News) – People who have recovered from severe COVID-19 may have stronger long-term immune protection against reinfection than those with milder illness, researchers report.
They examined some blood samples from 39 COVID-19 patients and 10 people who had not been exposed to the virus (their blood samples werepandemic). In total, they analyzed the expression of individual genes from more than 80,000 CD8 + T cells.
CD8 + T cells are immune cells that destroy host cells infected with the virus, and “memory” CD8 + T cells protect the body from reinfection with many types of viruses.
Of the patients with COVID-19, 17 had milder illness and were not hospitalized, 13 had been hospitalized and nine ended up in intensive care. The researchers were surprised to find that patients with milder COVID-19 had weaker CD8 + T cell responses.
The strongest CD8 + T cell responses were seen in critically ill patients who required hospitalization or intensive care.
“There is an inverse link between poorly functioning T cells and the severity of the infection,” said study co-author Dr Christian Ottensmeier in a press release from the La Jolla Institute for immunology in California. He is a professor at the University of Liverpool in the United Kingdom and an assistant professor at the La Jolla Institute.
Researchers found that CD8 + T cells in people with mild COVID-19 showed signs of “depletion” of T cells, in which cells receive so much immune system stimulation to fight viruses as they become less effective.
T cell depletion in people with mild COVID-19 may reduce their chances of immunity, according to the authors.
“People with serious illness are likely to end up with a good number of memory cells,” said study co-author Pandurangan Vijayanand, professor at the La Jolla Institute. “People with milder disease have memory cells, but they seem exhausted and dysfunctional – so they might not be effective for long enough.”
The results “suggest that people with severe cases of COVID-19 may have stronger long-term immunity,” Vijayanand said.
This study highlights the enormous variability in the way humans respond to a viral challenge, Ottensmeier said.
Although the study offers important new information about the immune response of COVID-19 patients, it is limited due to its dependence on CD8 + T cells found in blood samples, the researchers explained.
To find out more, they plan to assess T cells in the tissues most affected by the new coronavirus, like the lungs, to see how they react to the virus. This is crucial because the memory T cells that provide long-term immunity must live in the tissues.
The study was published on January 21 in the journal Scientific immunology.
US Centers for Disease Control and Prevention has more on COVID-19[female[feminine.
SOURCE: La Jolla Institute of Immunology, press release, January 21, 2021