CD4+ T cells from food allergy model are resistant to TCR-dependent apoptotic induction

• Lower levels of IL-18 were detected in allergic mice.
• IL-18 enhances the therapeutic effect of specific immunotherapy.
• IL-18 increased the TCR-dependent CD4+ T cell apoptosis.

BackgroundCD4+ T cell polarization plays a critical role in the pathogenesis of allergy. How to modulate the skewed CD4+ T cell polarization is less clear. The specific immunotherapy (SIT) is the only specific remedy for the treatment of allergic diseases; the therapeutic effect is to be improved.ObjectivesThis study aims to investigate the role of interleukin (IL)-18 in enhancing the therapeutic effect of SIT.MethodsA peanut allergy mouse model was developed and treated with SIT or/and IL-18. CD4+ T cell apoptosis was assessed by flow cytometry. The expression of Fas ligand (FasL) was observed by quantitative real time RT-PCR and Western blotting. Interferon-γ in the culture medium was determined by enzyme-linked immunosorbent assay. The fasL gene promoter methylation in CD4+ T cells was assessed by methylation specific PCR.ResultsThe results showed that lower levels of IL-18 were detected in allergic mice; administration of IL-18 significantly enhanced the therapeutic effect of SIT on suppressing the allergic inflammation in the mouse intestine. In the cell culture studies, IL-18 increased the TCR-dependent CD4+ T cell apoptosis, the expression of FasL in CD4+ T cells, the production of Interferon-γ and the demethylation of the FasL promoter in CD4+ T cells.ConclusionsAdministration of IL-18 enhances the effect of SIT on suppressing allergic inflammation in the mouse intestine via enhancing the TCR-dependent CD4+ T cell apoptosis.