CD86 and COVID-19: The reduction and functional exhaustion of T cells was closely related to the suppression of antigen-presentation cells, and the reduction in the expression levels of CD86 and HLA-DR on monocytes and mDCs was most pronounced in severe COVID-19 patients, evidenced by CITE-seq analysis, phspho-CyTOF and single-cell transcriptome data (Arunachalam et al., 2020).