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

Next, we analyzed the expression of the phenotypic markers on the FSC-high population using flow cytometry. As shown in Figure 2A -B, these cells are strongly positive for CD14 and CD16, suggesting that they belong to the monocyte lineage. More importantly, macrophage markers CD11b, CD68, CD80, CD163, CD206 are all expressed in this population. Since CD80 is considered a marker typical of M1 polarization, and CD163 and CD206 are considered to be typical of M2 polarization, it suggests that the FSC-high population contains both M1 and M2 macrophages. To further confirm this suspicion, we performed intracellular staining to validate the expression of M1/M2-specific cytokines in the FSC-high cells. As shown in Figure 2C -D, M1-specific cytokines IL-6 and TNF-α were found to be secreted, while on the other hand, the M2-specific cytokine IL-10 was also expressed by cells in the FSC-high population. Collectively, these findings strongly support that the FSC-high population in COVID-19 are composed of macrophages that have a mixed M1 and M2 polarization. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.