Killer cells stronger than antibodies.
A key player in the immune response to the coronavirus remains effective against the more contagious variants of Covid-19 and against the increased risks of reinfection, according to a study published on Tuesday.
The action of T lymphocytes, called "killer T cells" because they kill infected cells, is part of the immune response, along with antibodies, and helps prevent the more severe forms of the disease.
Scientists from the US National Institutes of Health (NIH) and Johns Hopkins University analyzed blood samples from 30 people who contracted the virus before the variants emerged.
The study, published in the Oxford University journal Open Forum Infectious Diseases, investigated whether these CD8 T cells (the technical name for these white blood cells) were able to recognize the three major variants of SARS-CoV- 2: B.1.1.7 (appeared in England), B.1.351 (identified in South Africa) and B.1.1.248 (reported in Brazil).
Most intact cell response
They each carry a mutation in the region of the S protein (spike), “spikes” on the surface of the virus which allow it to attack human cells, in particular in the case of B.1.351.
These mutations make the variant less recognizable for neutralizing antibodies, the other part of the immune response.
In the case of the coronavirus, these antibodies attach themselves to the tip to prevent the virus from infecting cells.
T lymphocytes are responsible for "killing" already infected cells.
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The study shows that the response of "killer cells" remains mostly intact and that they can recognize virtually all variants, unlike antibodies, but if the researchers believe that larger studies are needed to confirm this result.