Probiotics and the immunological response to infant vaccinations; a double-blind randomized controlled trial

Objectives: To examine the effect of a combination of probiotics on the antibody response to pneumococcal and pertussis vaccination in healthy Danish children, aged 8-14 months, at the time of starting day care. Moreover, the cytokine response to lipopolysaccharide of whole blood was assessed. Methods: A total of 290 children were randomly allocated to receive a combination of Bifidobacterium animalis ssp. lactic and Lactobacillus rhamnosus GG daily for a 6-month intervention period, and blood samples were drawn at the start and end of the study. Specific antibody response towards Streptococcus pneumoniae serotypes and Bordetella pertussis toxin, as well as endotoxin-induced interleukin-6 (IL-6) and interferon-gamma (IFN-gamma) production in blood were analysed by Luminex and ELISA. Results: There was no significant difference between the average individual changes from baseline to end of study in antibody concentrations for S. pneumoniae for both the probiotics (340.4% +/- 11.2%) and the placebo group (382.9% +/- 10.4%) (p 0.525), nor for B. pertussis toxin in the two groups (probiotics 190.1% +/- 12.6% versus placebo 238.8% +/- 1.1%, p 0.340). The average individual change in IL-6 concentration was significantly lower in the probiotics versus the placebo group (2.9% +/- 10.3% versus 33.7% +/- 9.0%, p 0.024), whereas there was no difference in IFN-gamma concentration (0.0% +/- 0.2% versus - 0.2% +/- 0.1%, p 0.279). Conclusions: The probiotic intervention did not affect the antibody response against S. pneumoniae and B. pertussis toxin in healthy Danish children. (C) 2018 The Authors. Published by Elsevier Ltd on behalf of European Society of Clinical Microbiology and Infectious Diseases.