TREM-1 expression on neutrophils and monocytes of septic patients: relation to the underlying infection and the implicated pathogen

Peripheral venous blood was sampled from 125 patients with sepsis and 88 with severe sepsis/septic shock. The causative pathogen was isolated in 91 patients. Patients were suffering from acute pyelonephritis, community-acquired pneumonia (CAP), intra-abdominal infections (IAIs), primary bacteremia and ventilator-associated pneumonia or hospital-acquired pneumonia (VAP/HAP). Blood monocytes and neutrophils were isolated. Flow cytometry was used to estimate the TREM-1 expression from septic patients.Within patients bearing intrabdominal infections, expression of TREM-1 was significantly lower on neutrophils and on monocytes at severe sepsis/shock than at sepsis. That was also the case for severe sepsis/shock developed in the field of VAP/HAP. Among patients who suffered infections by Gram-negative community-acquired pathogens or among patients who suffered polymicrobial infections, expression of TREM-1 on monocytes was significantly lower at the stage of severe sepsis/shock than at the stage of sepsis.Decrease of the expression of TREM-1 on the membrane of monocytes and neutrophils upon transition from sepsis to severe sepsis/septic shock depends on the underlying type of infection and the causative pathogen.Septic syndrome is one of the leading causes of death. Its great lethality had led to several randomized trials of the administration of various types of immunotherapy. The concept of all these types of therapeutic approach was to modulate the exaggerated immune response of the host [1]. However most of results were disappointing. Several probable explanations for these failures have been given; among them the heterogeneity of patients is the most likely. This probably has to do with the type of underlying infection, the causative microorganism and the co-morbid conditions. In a recent prospective study of the Hellenic Sepsis Study Group http://www.sepsis.gr webcite 505 patients were enrolled; changes of the innate and adaptive immunity were evaluated with immunop