Examination of other inhibitory receptors, CD72 and CD22, revealed that there was a significant increase in expression level of CD72 on DN3 cells from mild SARS-CoV-2 compared to heathy controls, such that DN3 cells from subjects with severe SARS-CoV-2 infection have significantly lower levels of CD72 expression than from mild infection (Figures 5A, B). This evidence concerns the gene CD22 and infection.