Background: The suppressive function of regulatory T (Treg) cells is compromised in allergic individuals, and the augmentation of Treg cells has been demonstrated after successful allergen immunotherapy.
Objective: To evaluate the effect of Dermatophagoides farinae fragments (Der f 2 N-peptides) that do not bind specific IgE in conjunction with the fungal immunomodulatory peptide fve (FIP-fve) on Treg cells derived from individuals with allergic rhinitis.
Methods: CD4+CD25+ T cells were isolated from peripheral blood mononuclear cells of 11 patients with allergic rhinitis and 7 nonallergic individuals using immunomagnetic beads. Cells were cultured with medium, Der f 2, FIP-fve, FIP-fve plus Der f 2, and FIP-fve plus Der f 2 N-peptides for 6 days in the presence of antigen-presenting cells. The percentages and function of Foxp3+CD4+CD25+ Treg cells, interleukin (IL) 10+, and transforming growth factor beta (TGF-beta)+ Treg cells were measured.
Results: The percentage of Foxp3+ Treg cells in CD4+CD25+ T cells was significantly increased in D farinae allergic patients by Der f 2 N-peptides in conjunction with FIP-fve. Both IL-10+ and TGF-beta+ Treg cells were significantly increased in the presence of Der f 2 N-peptides and FIP-fve compared with other groups. The function of Treg cells induced by Der f 2 N-peptides and FIP-fve could be demonstrated by the inhibition of bromodeoxyuridine uptake by peripheral blood mononuclear cells.
Conclusion: The percentage of IL-10+ and TGF-beta+ cells in Foxp3+CD4+CD25+ T cells can be up-regulated by Der f 2 N-peptides in conjunction with FIP-fve only in D farinae allergic individuals. These results indicate that non-IgE-mediated fragments of allergen in conjunction with FIP-fve might have therapeutic effects on Treg cells derived from allergic individuals.