CRP-XL dose escalation leads to increased aggregation and activation of platelets in sepsis. Platelet reactivity of healthy controls (HC) and patients with sepsis (S) was depicted upon stimulation with CRP-XL standard dose (C) (0.1 µg/mL in aggregometry; 0.01 µg/mL in flow cytometry) or CRP-XL high dose (CHi) (1 µg/mL) (A-B) Platelet activation due to integrin activation indicated through PAC-1 binding (A) or P-selectin exposure (B) was assessed in whole blood by flow cytometry. (C-D) Light transmission aggregometry was performed using washed platelets (500 000/µL). Samples were measured for 5 minutes. Representative curves are shown in panel C. (E-F) Platelets were lysed after 5 minutes of CRP-XL stimulation or resting conditions. Staining was performed with phosphotyrosine antibody 4G10. Band intensity (72 kDa) was set in relation to a housekeeping protein in AU. Representative blots are shown in panel E (time point I). All graphs show median ± IQR.