One of the first peer-reviewed studies on the coronavirus and T cells was published in mid-May in the journal Cell by Alessandro Sette, Shane Crotty and others at the La Jolla Institute for Immunology near San Diego.
The group was researching blood from people who were recovering from coronavirus infections and wanted to compare that to samples from uninfected controls who were donors to a blood bank from 2015 to 2018. The researchers were floored to find that in 40 to 60 percent of the old samples, the T cells seemed to recognize SARS-CoV-2.
“The virus didn’t even exist back then, so to have this immune response was remarkable,” Sette said.
Research teams from five other locations reported similar findings. In a study from the Netherlands, T cells reacted to the virus in 20 percent of the samples. In Germany, 34 percent. In Singapore, 50 percent.
The different teams hypothesized this could be due to previous exposure to similar pathogens. Perhaps fortuitously, SARS-CoV-2 is part of a large family of viruses. Two of them — SARS and MERS — are deadly and led to relatively brief and contained outbreaks. Four other coronavirus variants, which cause the common cold, circulate widely each year but typically result in only mild symptoms. Sette calls them the “less-evil cousins of SARS-CoV-2.”
This week, Sette and others from the team reported new research in Science providing evidence the T cell responses may derive in part from memory of “common cold” coronaviruses.
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