Short wheat challenge is a reproducible in‐vivo assay to detect immune response to gluten

Summary It has been reported that interferon (IFN)‐γ‐secreting T cells reactive to gluten can be detected in the peripheral blood of individuals with treated coeliac disease (CD) after a short consumption of wheat‐containing food. By contrast, very little is known about the reproducibility of this in‐vivo procedure in the same patient cohort which underwent two, or more, gluten consumptions. Fourteen coeliac patients in remission consumed wheat bread for 3 days; 13 underwent a second gluten challenge after a wash‐out of 3–10 months on a strict gluten‐free diet. Immune reactivity to gluten was analysed in peripheral blood by detecting IFN‐γ before and 6 days after commencing a gluten diet. Gliadin‐specific IFN‐γ‐secreting CD4+ T cells increased significantly on day 6 of the first challenge. These cells resulted as prevalently human leucocyte antigen (HLA)‐DQ restricted and with a phenotype of gut homing, as suggested by the expression of β7‐integrin. Similarly, reactiveness to gliadin was observed after the second wheat consumption, although with an individual variability of responses at each challenge. Our findings confirmed that the short wheat challenge is a non‐invasive approach to investigate the gluten‐related immune response in peripheral blood of subjects intolerant to gluten. Furthermore, we demonstrated that the in‐vivo procedure can be reproduced in the same subject cohort after a gluten wash‐out of at least 3 months. Our study has important implications for the application of this procedure to clinical practice.