Both endothelial and immune dysfunction contribute to the high mortality rate in human sepsis, but the underlying mechanisms are unclear. In response to infection, interferon-γ activates indoleamine 2,3-dioxygenase (IDO) which metabolizes the essential amino acid tryptophan to the toxic metabolite kynurenine. IDO can be expressed in endothelial cells, hepatocytes and mononuclear leukocytes, all of which contribute to sepsis pathophysiology. Increased IDO activity (measured by the kynurenine to tryptophan [KT] ratio in plasma) causes T-cell apoptosis, vasodilation and nitric oxide synthase inhibition. We hypothesized that IDO activity in sepsis would be related to plasma interferon-γ, interleukin-10, T cell lymphopenia and impairment of microvascular reactivity, a measure of endothelial nitric oxide bioavailability. In an observational cohort study of 80 sepsis patients (50 severe and 30 non-severe) and 40 hospital controls, we determined the relationship between IDO activity (plasma KT ratio) and selected plasma cytokines, sepsis severity, nitric oxide-dependent microvascular reactivity and lymphocyte subsets in sepsis. Plasma amino acids were measured by high performance liquid chromatography and microvascular reactivity by peripheral arterial tonometry. The plasma KT ratio was increased in sepsis (median 141 [IQR 64–235]) compared to controls (36 [28–52]); p

Abstract The aim of this study is to investigate prospectively specific immune system factors in preterm neonates with late-onset sepsis and infection-free controls. Matched preterm neonates ( n  = 82) were divided into three groups: suspected infection ( n  = 25), sepsis ( n  = 17), and infection-free controls ( n  = 40). Serial measurements were made of interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α), lymphocyte subsets [CD3+, CD4+, CD8+, natural killer (NK) cells, and B cells], the immunoglobulins (IgG, IgM, and IgA), C-reactive protein (CRP), and the total blood count, before, 2 days after initiation of treatment, and after stopping treatment. The percentages of NK and B cells were higher in the sepsis group, but those of CD3+, CD4+, and CD8+ showed no differences. IgG was lower in the sepsis group. IL-6 >30 pg/ml and TNF-α >30 pg/ml were sensitive sepsis predictors with sensitivity 1 (0.78–1) and 1 (0.79–1), respectively, but their specificity was poor. CRP was a specific [0.90 (0.80–0.96)] but not sensitive index [0.68 (0.48–0.85)], and its combination with IL-6 or TNF-α could enhance their diagnostic accuracy. It is concluded that NK and B cells may be elevated in late neonatal sepsis. IL-6 or TNF-α combined with CRP is a good diagnostic marker for late-onset sepsis in preterm neonates.

> The purpose of the study is to study the relationship between peripheral blood lymphocyte subset proportion and prognosis in patients with septic shock. Fifty-two patients with septic shock, admitted to the intensive care unit between March 2007 and December 2010, were enrolled in this study. Peripheral blood lymphocyte subset proportions were measured using flow cytometry. The percentage of CD3 + CD4 + T lymphocytes and CD19 + lymphocytes, CD4 + /CD8 + T cell ratio were substantially lower in patients with septic shock compared to the control group ( P + CD8 + T lymphocytes did not differ significantly between the two groups ( P > 0.05). The percentage of CD16 + CD56 + lymphocytes was higher in patients with septic shock than in the control group ( P + CD4 + T lymphocytes and CD19 + lymphocytes, CD4 + /CD8 + T cell ratio were clearly lower in the non-survivor group ( P + CD8 + T lymphocytes between the non-survivor and survivor groups ( P > 0.05). The percentage of CD16 + CD56 + lymphocytes was higher in the non-survivor group than in the survivor group ( P P