Platelet and leukocyte activation correlate with the severity of septic organ dysfunction

This study was conducted to investigate the extent of platelet-leukocyte adhesion and platelet, monocyte, and neutrophil activation in septic patients and to analyze whether these variables correlate with the severity of sepsis. Forty-seven patients consecutively admitted to the operative ICU of a University Medical Centre and 12 control patients prior to elective surgery were included in this prospective cohort study. Patients were evaluated daily for sepsis criteria and sepsis-associated organ failure assessment (SOFA) score was used to describe the extent of sepsis-associated organ failure. Indicators for cell activation (CD62P on platelets and CD11b on neutrophils and monocytes) and binding of platelets to neutrophils and monocytes were analyzed by flow cytometry. CD62P was increased on platelets from patients with sepsis compared with patients who did not have sepsis. Patients with sepsis also had higher CD11b expression on neutrophils and monocytes. Statistical analyses revealed a positive correlation between platelet CD62P expression and severity of sepsis, as well as a positive correlation between the SOFA score and CD11b on monocytes. No correlation was found between the SOFA score and CD11b on neutrophils. Higher values for platelet-neutrophil adhesion were observed in patients with uncomplicated sepsis compared either with controls or to patients with septic shock. An inverse relation between severity of sepsis and extent of platelet-neutrophil adhesion was also obvious from correlation analysis. The results indicate that flow cytometry can be used to measure these parameters of cell activation in sepsis and that activation of platelets and monocytes as well as adhesion of platelets to neutrophils does play a role in the development of organ dysfunction.