Background and aims: A number of lines of evidence suggest that the disappearance of helminths from human populations in developed countries may be responsible for the upsurge in autoimmune diseases, the so-called hygiene hypothesis. Using a small cohort of healthy subjects with quiescent celiac disease, our aim is to test if the ubiquitous hookworm (HW) of humans, Necator americanus, inhibits immune responsiveness to a gluten challenge (GC). As well as being of potential benefit to people with gluten intolerance, this study will provide the opportunity to undertake detailed investigation at the mucosal level of the host-parasite interaction, and the underlying immune response, and by extension, the potential of nematode infection to modulate the inflammatory response in IBD. Unlike experimental helminth infections in either animals genetically predisposed to colitis or in clinical IBD (where a range of complicating cofactors are present), this study addresses what happens in healthy humans who do not have a background of helminth exposure, and who are not currently compromised by either inflammation or immunosuppressive drugs.