Background The value of probiotics for primary prevention is controversial. Moreover, only little is known about the underlying immunological mechanisms of action. Therefore, we assessed the proliferative response and cytokine release in cultures of isolated mononuclear cells from pregnant women and their neonates supplemented with Lactobacillus GG (LGG) or placebo.
Methods In a double-blind, placebo-controlled prospective trial, pregnant women with at least one first-degree relative or a partner with an atopic disease were randomly assigned to receive either the probiotic LGG (ATCC 53103; 5 × 109 colony-forming units LGG twice daily) or placebo 4–6 weeks before expected delivery, followed by a post-natal period of 6 months. Cord blood mononuclear cells (CBMC) and peripheral blood mononuclear cells (PBMC) of the corresponding mother were isolated from cord blood and peripheral blood (n=68). The proliferative response of CBMC and PBMC was expressed as the stimulation index (SI), which was calculated according to the ratio between the mean counts per minute (c.p.m.) values measured in the wells with stimulated cells and the mean c.p.m. values measured in the wells with unstimulated cells. Additionally, the cytokines IFN-γ, IL-10 and IL-13 in the cell culture supernatants were measured using the ELISA technique.
Results No difference was observed between the LGG-supplemented group and the placebo group in terms of the proliferative capacity of maternal or neonatal cord blood cells in response to IL-2, β-lactoglobulin or LGG. In vitro stimulation with LGG resulted in significantly enhanced release of IL-10 and IFN-γ, compared with cytokine release in unstimulated controls. However, this phenomenon was observed in supernatants of maternal and neonatal MC in both groups, independent of prior supplementation with LGG.
Conclusion LGG has in vitro effects on enhanced IL-10 and IFN-γ release of mononuclear cells. However, supplementation with LGG during pregnancy did not alter the proliferative capacity or cytokine pattern in their recipients.