Aggregation and integrin α_IIbβ₃ activation are unaffected by COVID19 immune complexes. (Ai) Concentration response curves plotting platelet aggregation after stimulation with a range of type I collagen concentrations (from 10 μg/mL to 10 ng/mL) in the presence of immune complexes containing spike plus WT IgG or IgG with modified glycosylation and (Bi) plots of logEC₅₀ for collagen in the presence of the different treatments, the bars represent the mean ± SEM. (C) Fibrinogen binding to platelets measured by flow cytometry after stimulation with (Ci) 10 μM ADP, (Cii) 1 μg/mL CRP-XL, and (Ciii) 1 μM TRAP-6 in the presence of spike only or immune complexes containing WT IgG or IgG with modified glycosylation. Significant differences were tested by 2-way ANOVA with the Tukey multiple comparisons test. AFU, active fluorescence units; MFI, mean fluorescent intensity.