COVID-19 infection induces readily detectable morphological and inflammation-related phenotypic changes in peripheral blood monocytes, the severity of which correlate with patient outcome

Dan Zhang; Rui Guo; Lei Lei; Hongjuan Liu; Yawen Wang; Yili Wang; Tongxin Dai; Tianxiao Zhang; Yanjun Lai; Jingya Wang; Zhiqiang Liu; Aili He; Michael O'Dwyer; Jinsong Hu

ACE2 has been shown to be the entry receptor for both the SARS-CoV and SARS-CoV-2. [7] [8] [9] [10] Speculating that direct viral infection could trigger the observed changes in monocytes, we further investigated whether monocytes express ACE2 and therefore could be infected by the SARS-CoV-2. By performing flow cytometry staining ACE2 on human monocytic cell lines THP-1 and U939, as well as murine macrophage cell line RAW264.7, we demonstrated that all these monocyte/macrophage cells are ACE2 positive ( Figure 4A ). Moreover, we confirmed that the monocytes in the peripheral blood of the healthy donors and COVID-19 patients are positive ( Figure 4B-D) . More importantly, we found that the expression level of ACE2 on the monocytes/macrophages in COVID-19 patients is significantly lower than healthy donors ( Figure 4E ).