CD8(+) T cells specific for conserved coronavirus epitopes correlate with milder disease in patients with COVID-19

A central feature of the SARS-CoV-2 pandemic is that some individuals become severely ill or die, whereas others have only a mild disease course or are asymptomatic. Here, we report the development of an improved multimeric αβ T cell staining reagent platform, with each maxi-ferritin “spheromer” displaying 12 peptide-MHC complexes. Spheromers stain specific T cells more efficiently than peptide-MHC tetramers and capture a broader portion of the sequence repertoire for a given peptide-MHC. Analyzing the response in unexposed individuals, we find that T cells recognizing peptides conserved among coronaviruses are more abundant and tend to have a “memory” phenotype compared with those unique to SARS-CoV-2. Notably, CD8(+) T cells with these conserved specificities are much more abundant in patients with mild COVID-19 versus those with a more severe illness, suggesting a protective role.