CD27 and COVID-19: In this context, we demonstrated that the high median fluorescence intensity ratio of CD169 between monocytes and lymphocytes (CD169 RMFI) in COVID-19 patients correlated with CD8 T-cell senescence and exhaustion (CCR7, CD45RA, CD28, CD27, CD57), and with B-cell maturation and differentiation markers (CD45, CD19, CD27, IgM, IgD).