T cells memory in exposed vs unexposed individuals to COVID 19

T cells memory in exposed vs unexposed individuals to COVID 19

Context: In Covid-19 patients whose symptoms were mild, researchers found that they were more likely than sicker patients to have signs of prior infection by similar, less virulent coronaviruses. The study, by researchers from the Stanford University School of Medicine researchers, has been published in the journal Science Immunology.

Concept:

The findings suggest that people with Covid-19 may experience milder symptoms if certain cells of their immune systems “remember” previous encounters with seasonal coronaviruses.

Exposed

• The immune cells are killer T cells. The study showed that killer T cells taken from the sickest Covid-19 patients exhibit fewer signs of having previous ruins with common-cold-causing coronaviruses.
• Human cells routinely saw up some samples of each protein they’ve made into tiny pieces, and display those pieces (called peptides) on their surfaces, so that T cells can inspect them. When a killer T-cell notices a peptide that doesn’t belong on a cell’s surface, it multiplies furiously, and its numerous offspring fire up to destroy any cell carrying these peptides.

Unexposed

• It is found that unexposed individuals’ killer T cells targeting SARS-CoV-2 peptides that were shared with other coronaviruses were more likely to have proliferated than killer T cells targeting peptides found only on SARS-CoV-2.
• The T cells targeting those shared peptide sequences had probably previously encountered one or another gentler coronavirus strain, and had proliferated in response