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Background: Current understanding of T cell epitopes in coeliac disease (CD) largely derives from intestinal T cell clones in vitro. T cell clones allow identification of gluten peptides that stimulate T cells but do not quantify their contribution to the overall gluten specific T cell response in individuals with CD when exposed to gluten in vivo. Aims: To determine the contribution of a putative dominant T cell epitope to the overall gliadin T cell response in HLA- DQ2 CD in vivo. Patients: HLA- DQ2+ individuals with CD and healthy controls. Methods: Subjects consumed 20 g of gluten daily for three days. Interferon γ (IFN- γ ) ELISPOT was performed using peripheral blood mononuclear cells (PBMC) to enumerate and characterise peptide and gliadin specific T cells before and after gluten challenge. Results: In 50/59 CD subjects, irrespective of homo- or heterozygosity for HLA- DQ2, IFN- γ ELISPOT responses for an optimal concentration of A- gliadin 57- 73 Q- E65 were between 10 and 1500 per million PBMC, equivalent to a median 51% of the response for a “ near optimal“ concentration of deamidated gliadin. Whole deamidated gliadin and gliadin epitope specific T cells induced in peripheral blood expressed an intestinal homing integrin (α 4β 7) and were HLA- DQ2 restricted. Peripheral blood T cells specific for A- gliadin 57- 73 Q- E65 are rare in untreated CD but can be predictably induced two weeks after gluten exclusion. Conclusion: In vivo gluten challenge is a simple safe method that allows relevant T cells to be analysed and quantified in peripheral blood by ELISPOT, and should permit comprehensive high throughput mapping of gluten T cell epitopes in large numbers of individuals with CD.
Background: Current understanding of T cell epitopes in coeliac disease (CD) largely derived from intestinal T cell clones in vitro. T cell clones allow identification of gluten peptides that stimulate T cells but do not quantify their contribution to the overall gluten specific T cell response in individuals with CD when exposed to gluten in vivo. Aims: To determine the contribution of a putative dominant T cell epitope to the overall gliadin T cell response in HLA-DQ2 CD in vivo. Patients: HLA-DQ2 + individuals with CD and healthy controls . Methods: Subjects consumed 20 g of gluten daily for three days. Interferon γ (IFN- γ) ELISPOT was performed using peripheral blood mononuclear cells (PBMC) to enumerate and characterise peptide and gliadin specific T cells before and after gluten challenge. In 50/59 CD subjects, irrespective of homo- or heterozygosity for HLA-DQ2, IFN- [gamma] ELISPOT responses for an optimal concentration of A-gliadin 57-73 Q-E65 were between 10 and 1 500 per million PBMC, equivalent to a median 51% of the response for a ”near optimal " concentration of deamidated gliadin. Whole deamidated gliadin and gliadin epitope specific T cells induced in peripheral blood expressed an intestinal homing integrin (α 4β 7) and were HLA-DQ2 restricted. Peripheral blood T cells specific for A-gliadin 57-73 Q- E65 are rare in untreated CD but can be predictably induced two weeks after gluten exclusion. Conclusion: In vivo gluten challenge is a simple safe method that allows relevant T cells to be analyzed and quantified in peripheral blood by ELISPOT, and should permit comprehensive comprehensive high throughput mapping of gluten T cell epitopes in large numbers of individuals with CD.