ACE2 and lymphopenia: Previously, the SARS-CoV virions and genomic sequence were analyzed in a great number of peripheral lymphocytes, causing the destruction of lymphocytes.18 Our finding offers a possible explanation for lymphopenia in COVID-19 cases.35 The expression of CD147 is reported to be elevated in inflammatory alveolar epithelial cells,36 and ACE2 is down-regulated by SARS-CoV infection.37 In the meanwhile, the expression level of CD147 is higher than that of ACE2 in Vero E6 cells and no expression of ACE2 is detected in BEAS-2B cells.