Regulatory T cells in children undergoing rush venom immunotherapy

Venom immunotherapy (VIT) induces immune tolerance to Hymenoptera venom but the underlying mechanisms are not clarified. Regulatory T cells are thought to play an important role in tolerance induction during specific immunotherapy. Our objective was to determine the effects of rush VIT on the percentage of regulatory T cells and immunosuppressive cytokines interleukin (IL)-10 and transforming growth factor beta (TGF-beta) in children. Blood samples were collected from 18 children with a previous systemic allergic reaction to a Hymenoptera sting, with a positive skin test and positive specific IgE, before rush VIT, after 6 weeks and 6 months of rush VIT. Ten children with no history of venom allergy were studied as controls. Isolated peripheral blood mononuclear cells were stained with specific markers for regulatory T cells and analyzed by flow cytometry. The percentage of regulatory T cells did not change during rush VIT in children. No change was noticed in the percentage of IL-10 and TGF-beta secreting cells after 6 weeks or 6 months of VIT. No difference in expression of cytotoxic T-lymphocyte antigen 4 on CD4(+)CD25(+high) was found. Rush VIT is a safe and effective treatment for patients allergic to Hymenoptera venom. Although regulatory T cells are considered to be responsible for this effect; no significant changes in the percentage of these cells or immunosuppressive cytokines were noticed during rush VIT in children. Additional investigations are needed to clarify the role of regulatory T cells in the induction of tolerance during rush VIT in children.