Figure 6
In vitro assessment of NET-osis is associated to clinical severity of COVID-19. High density neutrophils were isolated from three healthy subjects using a density gradient as described in Methods and previously44,45,46; purity was assessed as shown in Supplementary Fig. 1. After isolation, HDNs were maintained in culture with 10% FBS complete RPMI media for 2 h and exposed to sera obtained from healthy or COVID-19 subjects for 3 h. DAPI and cit-H3 staining of DNA revealed the presence of neutrophil extracellular traps (NETs), as shown in panels (A–D). (E) percentage of NET-s and (F) NET density were quantified and plotted. Bars represent mean and standard deviation. Stars denote ANOVA among the three COVID groups (mild, moderate, severe), *p < 0.005, ** p < 0.001. Correlation among the quantity of percentage of in-vitro NET-osis and amount of IL-1β (G), IFN-γ (H) and IL-6 (I) is shown. Color code: grey, healthy subjects; green, mild COVID-19; orange, moderate COVID-10, red, severe COVID-19. COVID-19 severity was defined according to qCSI, based on respiratory rate, pulse oximetry and oxygen flow rate.
