IntroductionAlthough major changes of the immune system have been described in sepsis, it has never been studied whether these may differ in relation to the type of underlying infection or not. This was studied for the first time.MethodsThe statuses of the innate and adaptive immune systems were prospectively compared in 505 patients. Whole blood was sampled within less than 24 hours of advent of sepsis; white blood cells were stained with monoclonal antibodies and analyzed though a flow cytometer.ResultsExpression of HLA-DR was significantly decreased among patients with severe sepsis/shock due to acute pyelonephritis and intraabdominal infections compared with sepsis. The rate of apoptosis of natural killer (NK) cells differed significantly among patients with severe sepsis/shock due to ventilator-associated pneumonia (VAP) and hospital-acquired pneumonia (HAP) compared with sepsis. The rate of apoptosis of NKT cells differed significantly among patients with severe sepsis/shock due to acute pyelonephritis, primary bacteremia and VAP/HAP compared with sepsis. Regarding adaptive immunity, absolute counts of CD4-lymphocytes were significantly decreased among patients with severe sepsis/shock due to community-acquired pneumonia (CAP) and intraabdominal infections compared with sepsis. Absolute counts of B-lymphocytes were significantly decreased among patients with severe sepsis/shock due to CAP compared with sepsis.ConclusionsMajor differences of the early statuses of the innate and adaptive immune systems exist between sepsis and severe sepsis/shock in relation to the underlying type of infection. These results may have a major impact on therapeutics.

Our analysis positively validated the use of SOFA score to predict unfavourable outcome and to limit misclassification into lower severity. However, qSOFA score had inadequate sensitivity for early risk assessment.

In patients receiving hydrocortisone for septic shock, early initiation of treatment was associated with improved survival. This treatment was also associated with attenuated stimulation of tumor necrosis factor-α.

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How circulating inflammatory mediators change upon sepsis progression has not been studied. We studied the follow-up changes of circulating vasoactive peptides and cytokines until the improvement or the worsening of a patient and progression into specific organ dysfunctions. In a prospective study, concentrations of tumor necrosis factor-alpha (TNFα), interleukin (IL)-6, IL-8, IL-10, interferon-gamma (IFNγ), endocan and angiopoietin-2 (Ang-2) were measured in serum by an enzyme immunoassay in 175 patients at baseline; this was repeated within 24 h upon progression into new organ dysfunction (n = 141) or improvement (n = 34). Endocan and Ang-2 were the only parameters that were significantly increased among patients who worsened. Any increase of endocan was associated with worsening with odds ratio 16.65 (p < 0.0001). This increase was independently associated with progression into acute respiratory distress syndrome (ARDS) as shown after logistic regression analysis (odds ratio 2.91, p: 0.002). Changes of circulating cytokines do not mediate worsening of the critically ill patients. Instead endocan and Ang2 are increased and this may be interpreted as a key-playing role in the pathogenesis of ARDS and septic shock. Any increase of endocan is a surrogate of worsening of the clinical course.