Abstract
A report in Science Immunology, suggests some people with COVID-19 experience milder symptoms because CD8+ T cells ‘remember' previous encounters with seasonal corona-viruses.
In this case, these cells are better equipped to mobilize quickly against an infection with SARS-CoV-2. The study also showed that the killer T cells taken from the sickest COVID-19 patients exhibit fewer signs of having had previous run-ins with these coronaviruses.
Discussions about immunity to COVID-19 often center on antibodies. But antibodies are easily fooled, said senior author Mark Davis, of Stanford University. “Pathogens evolve quickly and ‘learn' to hide their critical features from our antibodies,” he noted. But T cells recognize pathogens in a different way, and they're tough to fool.
Davis and his colleagues found that COVID-19 patients with milder symptoms had more killer-T memory cells directed at peptides SARS-CoV-2 shared with other coronavirus strains. Sicker patients' expanded killer T-cell counts were mainly among those T cells typically targeting peptides unique to SARS-CoV-2 and, thus, probably had started from scratch in their response to the virus.