Low molecular weight fractions of BiMuno® exert immunostimulatory properties in murine macrophages

Previous in vivo murine oral challenge studies have shown that the galactooligosaccharide containing product, BiMuno (R), reduced colonisation of S. Typhimurium. To gain further insights into the mechanism of reduced colonisation, we wished to test the hypothesis that the low molecular weight fractions of BiMuno (R) or a specific low molecular weight fraction may have direct immuno-modulatory effects on murine macrophages. Cytokine responses of murine macrophages in response to the commercially available product, BiMuno (R), a basal solution BiMuno (R) without GOS, purified low molecular weight fractions (referred to as GOS), and the individual fractions of GOS (DP2, 3 and >= 4, with each fraction representing the increasing degree of complex polymerisation) were determined in vitro and ex vivo. These studies demonstrated that BiMuno (R), significantly stimulated both pro- and anti-inflammatory cytokines in vitro (P <= 0.0394). Furthermore, the data indicate that the low molecular weight fractions may be the primary stimulant of BiMuno (R) and specifically its tri (DP3) and >= tetra-saccharide (DP >= 4) fractions (P <= 0.0394). Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.