Decreased cytokine production by mononuclear cells after severe gram-negative infections: early clinical signs and association with final outcome

Abstract

Background: Failure of circulating monocytes for adequate cytokine production is a trait of sepsis-induced immunosuppression; however, its duration and association with final outcome are poorly understood.

Methods: We conducted a substudy of a large randomised clinical trial. Peripheral blood mononuclear cells (PBMCs) were isolated within the first 24 h from the onset of systemic inflammatory response syndrome in 95 patients with microbiologically confirmed or clinically suspected gram-negative infections. Isolation was repeated on days 3, 7 and 10. PBMCs were stimulated for cytokine production. The study endpoints were the differences between survivors and non-survivors, the persistence of immunosuppression, and determination of admission clinical signs that can lead to early identification of the likelihood of immunosuppression.

Results: PBMCs of survivors produced significantly greater concentrations of tumour necrosis factor-α (TNF-α), interleukin (IL)-6, IL-8, IL-10, interferon-γ and granulocyte-macrophage colony-stimulating factor after day 3. Using ROC analysis, we found that TNF-α production less than 250 pg/ml after lipopolysaccharide stimulation on day 3 could discriminate patients from healthy control subjects; this was associated with a 5.18 OR of having an unfavourable outcome (p = 0.046). This trait persisted as long as day 10. Logistic regression analysis showed that cardiovascular failure on admission was the only independent predictor of defective TNF-α production on day 3.

Conclusions: Defective TNF-α production is a major trait of sepsis-induced immunosuppression. It is associated with significant risk for unfavourable outcome and persists until day 10. Cardiovascular failure on admission is predictive of defective TNF-α production during follow-up.

Trial registration: ClinicalTrials.gov identifier: NCT01223690 . Registered on 18 October 2010.

Keywords: Immunosuppression; Prediction; Sepsis; Survival.

Figures

Fig. 1

Study flowchart. SIRS Systemic inflammatory response syndrome

Fig. 2

Cytokine production after stimulation with bacterial endotoxin. Cytokine production from medium-stimulated cells was below the limit of detection. White bars represent survivors and black bars non-survivors after 28 days of follow-up. p Values indicate statistically significant differences between survivors and non-survivors at the indicated time intervals. Non-significant differences are now shown. GM-CSF Granulocyte-macrophage colony-stimulating factor, IFN-γ Interferon-γ, IL Interleukin, TNF-α Tumour necrosis factor-α

Fig. 3

Cytokine production after stimulation with Pam3Cys. Cytokine production from medium-stimulated cells was below the limit of detection. White bars represent survivors and black bars non-survivors after 28 days of follow-up. p Values indicate statistically significant differences between survivors and non-survivors at the indicated time intervals. Non-significant differences are now shown. GM-CSF Granulocyte-macrophage colony-stimulating factor, IFN-γ Interferon-γ, IL Interleukin, TNF-α Tumour necrosis factor-α

Fig. 4

TNF-α production by LPS-stimulated PBMCs as an index of sepsis-induced immunosuppression. a Comparative production of TNF-α by PBMCs from healthy control subjects and patients after stimulation with LPS and Pam3Cys. The exact p values after correction for multiple testing are provided: a9.8 × 10−4; b2.5 × 10−3; c7.6 × 10−4; d5.7 × 10−4; enon-significant. b ROC curve analysis to identify a cut-off concentration of TNF-α produced by PBMCs after stimulation with LPS on day 3 between patients and healthy control subjects. c Survival analysis between patients with production of TNF-α less than 250 pg/ml (defective, n = 42) and patients with production of TNF-α more than 250 pg/ml (adequate, n = 46). p Values of significance are provided. LPS Lipopolysaccharide, PBMC Peripheral blood mononuclear cell, TNF-α Tumour necrosis factor-α