Platelet hyporeactivity is not inducible through bacteria or plasmatic factors but can be triggered by septic whole blood. P-selectin exposure and integrin activation are shown under resting conditions (−) and upon activation with 0.01 µg/mL CRP-X_L. (A-D) Whole blood of healthy donors was mixed with isolated patient-borne bacterial strains adjusted to defined optical density at 600 nm (OD₆₀₀) or with modified HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid)-buffered Tyrode solution (H). CD62P expression was analyzed on resting platelets (−) after 15 minutes. After incubation for 60 minutes, platelets were stimulated with CRP-X_L. (E) Platelets were incubated for 60 minutes in PPP of patients with sepsis (S) or healthy controls (HC) (n = 8). (F) Platelets were incubated for 15 minutes in whole blood of patients with sepsis (S) or healthy controls (HC) (n = 7). (A-D) The depicted data represent the mean. (E-F) The data represent mean ± standard error of the mean. Differences were analyzed using Wilcoxon matched-pairs signed rank test. *P < .05.