Figure 2: Cross-Linking of GPVI-Fc With Anti–Human-Fc IgG and Anti–Human-Fc Fab2 Increases Inhibition of Static Platelet Aggregation Induced by Collagen or Plaque Compared With GPVI-Fc

(A) Bar diagrams show the effects of glycoprotein VI–fragment crystallizable (GPVI-Fc) (20 μg/ml; 133 nM), GPVI-Fc, and Fc cross-linked (XL) with anti–human-Fc immunoglobulin G (IgG) (GPVI-Fc*IgG-XL, Fc*IgG-XL; 133 nM) (left panels) or with anti–human-Fc Fab2 (GPVI-Fc*Fab2-XL, Fc*Fab2-XL; 133 nM) (right panels) on plaque- or collagen-induced platelet aggregation. Further controls were anti–human-Fc IgG (133 nM) (left panels) and anti–human-Fc Fab2 (133 nM) (right panels). Cumulative platelet aggregation (AU*min) was measured by using multiple electrode aggregometry. Mean ± SD; n = 4. Repeated measures analysis of variance (overall p < 0.001) with secondary pair-wise comparisons (as indicated by bars) by Tukey correction. (B) Concentration dependency of the effects of GPVI-Fc*Fab2-XL on plaque- and collagen-induced platelet aggregation compared with GPVI-Fc. Mean ± SD; n = 4 to 6. Comparisons were made by using the Student t test or, if inappropriate, by using the Mann-Whitney U test (at 333 nM with plaque and at 33 nM with collagen). ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001.