Fig. 1

CLEC5A and TLR2 are responsible for SARS-CoV-2-induced NET formation. a, b Neutrophils (4 × 10⁵/ml) from healthy donors were incubated with SARS-CoV-2 (MOI = 1) with or without autologous platelets (4 × 10⁶/ml) for 5 h at 37 °C. The scale bar is 10 μm. The detailed structure of SARS-CoV-2-induced NET formation was observed under a confocal microscope (Leica). NET formation was visualized by fluorescent staining of DNA (blue), histone (green), and MPO (red) a NETs level was measured by MetaMorph software and presented as Cit-H3 area (μm²) (b). c Human neutrophils (4 × 10⁵/ml) were pretreated with anti-hCLEC5A mAb (3E12A2, 10 μg/ml), anti-TLR2 mAb (# MAB2616, 10 μg/ml), or combination of both antibodies for 30 min at room temperature, followed by incubation with SARS-CoV-2 (MOI = 0.1 and 1) in the presence or absence of platelets (4 × 10⁶/ml) for 5 h and 20 h. The level of NET formation was determined by histone area (μm²). d Neutrophils (4 × 10⁵/ml) from WT, clec5a^−/−, tlr2^−/−, and clec5a^−/−tlr2^−/− mice were incubated with SARS-CoV-2 (MOI = 1) in the presence or absence of WT platelets (4 × 10⁶/ml) for 5 h at 37 °C. e Human neutrophils were pre-treated with anti-hCLEC5A mAb (3E12A2, 100 μg/ml), anti-TLR2 mAb (# MAB2616, 100 μg/ml), or combination of both antibodies for 30 min at room temperature, followed by incubation with SARS-CoV-2 spike pseudotyped virus (MOI = 0.1) in the presence or absence of autologous platelets (4 × 10⁶/ml) for 3 h. Data are mean ± SEM and repeats of 3 to 5 independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 (Student’s t-test).