Fig. 3. VITT IgG induces thrombosis in FcγRIIa⁺/hPF4⁺ mice.

a Representative H&E staining of lung sections of mice treated with nIgG or VITT IgG. Scale bar 50 μm. b Fluorescent images of lung sections of mice treated with VITT IgG. Platelets and CitH3 were labelled in vivo with anti-CD42c-Dylight 649 (magenta) and AF594 (yellow). Neutrophil were stained with anti-Ly6G (green). Neutrophil infiltration in the clot is shown. Cell nuclei were stained with DAPI (blue). White arrows indicate areas of CitH3 staining. Asterisks indicate autofluorescence from red blood cells. Scale bars 50 μm. c Fluorescent images of lung sections of FcγRIIa⁺/hPF4⁺ mice treated with nIgG, VITT IgG or VITT IgG plus agIV.3 or FcγRIIa⁺/hPF4⁺/PAD4^−/− mice treated with VITT IgG. Fibrin labelled with AF594 (red) resulted from injection of AF594-labelled fibrinogen at 1 μg/g. Platelets were labelled in vivo with anti-CD42c-Dylight 649 (magenta). Cell nuclei were stained with DAPI (blue). Experiment was repeated independently (a) at least 10 times; b, c 3 times. Scale bar 10 μm. nIgG normal IgG, agIV.3 aglycosylated IV.3 antibody.