Humoral and cellular immunity to RSV in infants, children and adults.

BACKGROUND: Respiratory syncytial virus (RSV) causes respiratory disease throughout life. Here we report differences in naturally acquired immunity with age and presumed exposure. METHODS: A longitudinal, non-interventional, observational study was performed in healthy adults (20 paediatric healthcare workers and 10 non-healthcare workers), children (10 aged 3-6 years) and infants (5 aged 2-4 months and 20 aged 6-12 months). Blood samples were analysed for RSV-neutralising antibody titre, F/Ga/Gb-specific antibody titres, F-specific IgG/IgA memory B-cell frequencies and T-cell production of IFNγ, IL-4, IL-13 and IL-17. RESULTS: Serum G-specific antibody titres were significantly lower in infants and children than adults. However, serum titres of F-specific and RSV-neutralising antibody and IFNγ-producing T-cell frequencies were low or absent in the infants, but comparable between children and adults. Interestingly, F-specific memory IgA B-cells could not be detected in paediatric samples and in samples from non-healthcare workers, but recordable IgA memory B-cells were found in 9/18 paediatric healthcare workers and 2/8 non-healthcare workers at the end of the RSV season. These responses waned 4-6 months later. By contrast, F-specific IgG memory B-cells were detectable in samples from all adults without significant variation across time points. T-cells producing IL-4, IL-13 and IL-17 responses were not detectable in peripheral blood from a subset of volunteers. CONCLUSIONS: Repeated RSV exposure in early life generates immune responses that are inversely related to frequency of severe disease. Induction of F-specific antibody and cellular immune responses through infant vaccination might help to accelerate the development of protective immune responses at an early age. Clinicaltrials.gov reference NCT01563692 and NCT01640652.

Selenoprotein P, rather than glutathione peroxidase, as a potential marker of septic shock and related syndromes.

BACKGROUND/AIMS: Oxidative stress is involved in sepsis-related endothelium dysfunction. Selenoprotein-P (Sel-P), the main plasma selenoprotein, may have high antioxidant potential, and binds to endothelium. We hypothesize that, in septic shock, and similar syndromes such as systemic inflammatory response syndrome (SIRS), Sel-P binds massively to endothelium, causing a drop in Sel-P plasma concentration. METHODS: Plasma Se, Sel-P and albumin concentrations, and glutathione peroxidase (GPx) activity were measured in patients with septic shock and SIRS with organ failure (S group, n = 7 and n = 3, respectively) admitted to the intensive care unit (ICU) and compared to non-SIRS patients (NS group, n = 11) and healthy volunteers (HV group, n = 7). RESULTS: On ICU admission, plasma Sel-P concentrations were 70% lower in the S group than in the other groups [15 (10-26) vs. 44 (29-71) and 50 (45-53) nmol/l] and were lower in nonsurviving septic-shock patients. GPx activity did not differ between groups. Sel-P was significantly lower before ICU death in the 3 deceased patients of the S group (septic shock) than in the 3 patients of the non-SIRS group. CONCLUSIONS: Early decrease in Sel-P plasma concentrations was specifically observed in septic shock and was similar in SIRS patients whereas GPx activity remained unchanged. Further studies are needed to determine whether Sel-P can be an early marker of septic shock linked to microvascular injury.