Figure 2.

Effects of Syk and BTK inhibitors on platelet-dense granule secretion. Replicate samples (n = 3) of washed human platelets (2 × 10⁸/mL) were treated with the selected Syk and BTK inhibitors or vehicle (0.1% DMSO) and then stimulated with CRP-XL (A; 10 μg/mL) or thrombin (B; 1 Unit/mL). Platelet samples were monitored using ChromoLume (luciferase enzyme) to measure and record the luminescence kinetics of the dense granule ATP release profile of platelets, at 30-s intervals over the course of 5 min. Four kinetic profiles were recorded per platelet sample (n = 3). The average luminescence measured at 240 s was calculated and normalized by the average luminescence of the untreated platelets stimulated with CRP-XL or thrombin (+CRP-XL/−inhibitor or +thrombin/−inhibitor). Statistical analysis was performed using a one-way ANOVA test and a Dunnett’s multiple comparison test on GraphPad PRISM. Statistical significance is indicated by two asterisks (**) for a P value < 0.001. AVL, AVL-292 (spebrutinib); Bay, Bay 61-3606; BTK, Bruton’s tyrosine kinase; CG, CG-806; Fen, fenebrutinib; ONO, ONO-4059 (tirabrutinib); R406, fostamatinib; Syk, spleen tyrosine kinase; 935, BMS-935177; 986, BMS-986195; Ento, entospletinib; Ib, ibrutinib; TAK, TAK-659; Ro, Ro 31-8220; Aca, acalabrutinib; CRP-XL, cross-linked collagen-related peptide.