TLR3 and COVID-19: In this report, we demonstrate that COVID-19 plasma exosomes stimulate protein expression of TLR3 as well as TLR7 and TLR9 in CD4+ T cells, CD8+ T cells, and CD14+ monocytes compared with cells that remained untreated, treated with plasma exosomes from non-COVID-19 or healthy donors, or poly(I:C).