Humoral and cellular responses to gliadin in wheat-dependent, exercise-induced anaphylaxis

Wheat-dependent, exercise-induced anaphylaxis (WDEIA) is a severe allergy where wheat ingestion together with physical exercise induces anaphylaxis. We have previously shown that patients with WDEIA have IgE antibodies against gliadin proteins and identified omega-5 gliadin (Tri a 19) as a major allergen.

The aim of this study was to examine gliadin-specific IgG subclass, IgA and IgE antibodies, basophil histamine release and cell-mediated responses in WDEIA.

Sera and peripheral blood mononuclear cells (PBMC) were obtained from patients with WDEIA and from controls without wheat allergy. Serum antibodies to crude gliadin extract (CGE) and purified omega-5 gliadin were measured by ELISA and basophil reactivity by histamine-release test. Gliadin-induced cell-mediated responses were assessed by lymphocyte proliferation assay, and cytokine mRNA expression with real-time quantitative PCR.

All patients with WDEIA, but none of the controls, had IgE antibodies to CGE and omega-5 gliadin. Both allergens released high levels of histamine from the basophils of patients with WDEIA. Levels of IgA antibodies to CGE and omega-5 gliadin were significantly elevated in the patients, but the distribution of IgG subclass antibodies showed no statistically significant differences between the two groups. Proliferative responses of PBMC to CGE were increased in patients with WDEIA, and stimulation of PBMC with CGE caused, both in patients and in controls, a clear induction of IL-10 mRNA. Compared with the controls, induction of IL-10 mRNA expression in patients with WDEIA was significantly (P < 0.01) suppressed.

These results suggest that, in addition to IgE antibodies against omega-5 gliadin, specific IgA antibodies may be involved in the pathogenesis of WDEIA. Decreased expression of IL-10 mRNA in PBMC during gliadin stimulation may facilitate the development of gliadin-specific T cell responses.