Dissecting the T-cell response to hordeins in coeliac disease can develop barley with reduced immunotoxicity

Abstract

Background: Wheat, rye and barley prolamins are toxic to patients with coeliac disease. Barley is diploid with pure inbred cultivars available, and is attractive for genetic approaches to detoxification.

Aim: To identify barley hordein fractions which activated the interferon-γ (IFN-γ) secreting peripheral blood T-cells from coeliac volunteers, and compare immunotoxicity of hordeins from experimental barley lines.

Methods: To reactivate a T-cell response to hordein, volunteers underwent a 3-day oral barley challenge. Peripheral blood mononuclear cells (PBMC) were isolated from twenty-one HLA DQ2(+) patients with confirmed coeliac disease. IFN-γ ELISpot assays enumerated T-cells activated by purified prolamins and positive controls.

Results: Hordein-specific T-cells were induced by oral barley challenge. All prolamin fractions were immunotoxic, but D- and C-hordeins were most active. Barley lines lacking B- and C-hordeins had a 5-fold reduced hordein-content, and immunotoxicity of hordein extracts were reduced 20-fold compared with wild-type barley.

Conclusions: In vivo oral barley challenge offers a convenient and rapid approach to test the immunotoxicity of small amounts of purified hordeins using fresh T-cells from patients in high throughput overnight assays. Barley lines that did not accumulate B- and C-hordeins were viable, yet had substantially reduced immunotoxicity. Creation of hordein-free barley may therefore be possible.