Fig. 2

Impaired homeostasis of circulating neutrophils in COVID-19 patients. a–c Analysis of senescent and immunosuppressive neutrophil subsets in COVID-19 patients. Whole-blood samples were incubated for 45 min at 4 °C with Pe-Cy7-anti-human CXCR4, PE-anti-human CD11b, and APC-anti-human CD62L (a) or with FITC-anti-human CD16, PE-anti-human CD11c, Pe-Cy7-anti-human CD11b, and APC-anti-human CD62L (b) antibodies. a Percentages of the CXCR4^bright/CD62L^dim senescent PMN subset. b Percentages of the CD16^bright/CD62L^dim immunosuppressive PMN subset. (c) Ratio between the senescent and the immunosuppressive PMN subsets. d–h Analysis of the angiogenic neutrophil subset in COVID-19 patients. Whole-blood samples were incubated for 45 min at 4 °C with FITC-anti-human VEGF-R1 and BV-481-anti-human CD49d. d Representative dot plot of angiogenic CD49d^bright neutrophils gated according to forward-scattered light (FSC)/CD49d expression. e Percentages of the CD49d^bright angiogenic neutrophil subset. f Expression of CD49d expression was analyzed at the surface of angiogenic neutrophils (CD49d^bright); results are expressed in MFI. g One histogram representative of VEGF-R1 expression on angiogenic neutrophils from a control (white) and a COVID-19 patient (black). h Expression of VEGF-R1 on angiogenic neutrophils; results are expressed as MFI. Samples came from age-matched healthy controls (HCs) (n = 38), CAP patients (n = 22) and COVID-19 patients at day 1 (n = 53), day 3 (n = 49) and day 7 (n = 40). i Soluble VEGF-R1 was quantified by ELISA in HCs and COVID-19 patients at day 1 (n = 82), day 3 (n = 33) and day 7 (n = 32); results are as pg/ml. Values are means ± SEM. j Correlation between expression of VEGF-R1 on angiogenic neutrophils and soluble VEGF-R1 in COVID-19 patients. *P < 0.05, **P < 0.01, ***P < 0.001, adjusted for age. Samples came from age-matched healthy controls (HCs) (n = 38), CAP patients (n = 22) and COVID-19 patients at day 1 (n = 53), day 3 (n = 49) and day 7 (n = 40)