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Direct regulatory immune activity of lactic acid bacteria on Der p 1-pulsed dendritic cells from allergic patients.

Pochard P, Hammad H, Ratajczak C, Charbonnier-Hatzfeld AS, Just N, Tonnel AB, Pestel J

Unité INSERM U 416, Institut Pasteur de Lille, France.

BACKGROUND: Lactic acid bacteria (LAB) are suggested to play a regulatory role in the development of allergic reactions. However, their potential effects on dendritic cells (DCs) directing the immune polarization remain unclear. OBJECTIVE: The immunologic effect of Lactobacillus plantarum NCIMB 8826 (LAB1) on monocyte-derived dendritic cells (MD-DCs) from patients allergic to house dust mite was evaluated. METHODS: MD-DCs were stimulated for 24 hours with the related allergen Der p 1 in the presence or absence of LAB1. Cell-surface markers were assessed by means of FACS analysis, and the key polarizing cytokines IL-12 and IL-10 were quantified. The subsequent regulatory effect of pulsed MD-DCs on naive or memory T cells was evaluated by determining the T-cell cytokine profile. RESULTS: LAB1 induced the maturation of MD-DCs, even if pulsed with Der p 1. Interestingly, after incubation with LAB1 and Der p 1, MD-DCs produced higher amounts of IL-12 than Der p 1-pulsed DCs. Indeed, the T H 2 cytokine (IL-4 and IL-5) production observed when naive or memory autologous T cells were cocultured with Der p 1-pulsed MD-DCs was highly reduced in the presence of LAB1. Finally, in contrast to naive or memory T cells exposed once to Der p 1-pulsed DCs, T cells stimulated by MD-DCs pulsed with Der p 1 and LAB1 failed to produce T H 2 cytokines in response to a new stimulation with Der p 1-pulsed DCs. CONCLUSION: Thus in the presence of LAB1, MD-DCs from allergic patients tend to reorientate the T-cell response toward a beneficial T H 1 profile.

Published 1 July 2005 in J Allergy Clin Immunol, 116(1): 198-204.
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