Decrease of Non-Classical and Intermediate Monocyte Subsets in Severe Acute SARS-CoV-2 Infection

Abstract

In patients with severe SARS-CoV-2 infection, the development of cytokine storm induces extensive lung damage, and monocytes play a role in this pathological process. Non-classical (NC) and intermediate (INT) monocytes are known to be involved during viral and bacterial infections. In this study, 30 patients with different manifestations of acute SARS-CoV-2 infection were investigated with a flow cytometric study of NC, INT, and classical (CL) monocytes. Significantly reduced NC and INT monocytes and a downregulated HLA-DR were found in acute patients with severe SARS-CoV-2 symptoms. Conversely in patients with moderate symptoms NC and INT monocytes and CD11b expression were increased. © 2020 International Society for Advancement of Cytometry.

Keywords: COVID-19; SARS-CoV2; classical monocytes; intermediate monocytes; monocytes; multicolor flow cytometry; non-classical monocytes.

Figure 1

(A) Monocyte subsets and monocyte CD11b expression in a COVID‐19 patient with moderate clinical manifestations. Monocytes are gated with CD64 and monocyte subsets are dissected with a CD14/CD16 plot. (B) The same analysis in a severely infected patient. The profound decrease of the intermediate (INT) and non‐classical (NC) monocyte subsets and the lack of CD11b up‐regulation is evident in the severely infected subject. [Color figure can be viewed at wileyonlinelibrary.com]

Figure 2

Flow cytometric analysis of monocytes in patients and controls. (A) INT, NC, and CL monocyte subset frequencies, expressed as percentage of total monocytes. (B) Quantitative expression of monocyte CD11b‐APC and HLA‐DR‐V450 (geometric means in MFI units). Red asterisks indicate outliers. P values not significant unless otherwise specified. [Color figure can be viewed at wileyonlinelibrary.com]