Background Recent studies have implicated CD4+CD25+ regulatory T cells (nTregs) in the maintenance of tolerance to oral antigens and in the regulation of the food allergic IgE response.
Objective The objective was to assess if nTregs can transfer allergen-specific oral tolerance to naïve, non-TCR transgenic mice and regulate peanut extract (PE)-specific hypersensitivity responses. Additionally, the role of the regulatory cytokines IL-10 and TGF-β in the modulation of peanut-allergic sensitization was studied.
Methods CD25-enriched T cells from PE-tolerant mice were adoptively transferred to recipient mice, which were subsequently sensitized to PE. Depletion of CD25+ cells and neutralization of IL-10 and TGF-β were compared in a CH3/HeOuJ mouse model of peanut-allergic sensitization.
Results Transfer of CD25+ Tregs-enriched cell populations did not affect the PE-specific cytokine production or PE-specific antibody levels compared with control mice but interestingly resulted in a decrease of mast cell responsiveness. On the contrary, transfer of CD25+ Tregs-depleted cells caused an increase in non-specific cytokine production, in the absence of changes in PE-specific responses. TGF-β neutralization resulted even in a larger increase in spontaneous release of all cytokines measured (IL-4, IL-5, IL-10, IL-13, and IFN-γ), but surprisingly also to a higher PE-specific Th2-associated (IL-4, IL-5, IL-13) cytokine production compared with depletion of CD25 cells or neutralization of IL-10. Similarly, depletion of CD25 cells and TGF-β neutralization but not of IL-10 neutralization lead to an increase in PE-specific antibody levels and elevated mast cell degranulation following a PE challenge.
Conclusions and Clinical Relevance We conclude that CD4+CD25+ Tregs from non-transgenic-tolerant mice cannot transfer specific oral tolerance of exogenous antigens to naïve mice and are more involved in general immune suppressive mechanisms. However, we found evidence that TGF-β secreting Tregs (Th3) may play an important role.
Cite this as: M. Marcondes Rezende, I. Hassing, M. Bol-Schoenmakers, R. Bleumink, L. Boon, J. van Bilsen and R. Pieters, Clinical & Experimental Allergy, 2011 (41) 1324–1333.