BACKGROUND Food allergy is a common complaint among patients with a broad spectrum of abdominal and extra-abdominal symptoms that must be distinguished from other more common non-immunological food intolerances.

AIMS To investigate whether human intestinal hypersensitivity reactions are associated with detectable release of inflammatory mediators from activated cells, which may serve as a biological marker of true allergic reactions.

PATIENTS/METHODS In eight patients with food allergy and seven healthy volunteers, a closed-segment perfusion technique was used to investigate the effects of jejunal food challenge on luminal release of tryptase, histamine, prostaglandin D₂, eosinophil cationic protein, peroxidase activity, and water flux.

RESULTS Intraluminal administration of food antigens induced a rapid increase in intestinal release of tryptase, histamine, prostaglandin D₂, and peroxidase activity (p<0.05 v basal period) but not eosinophil cationic protein. The increased release of these mediators was associated with a notable water secretory response.

CONCLUSIONS These results suggest that human intestinal hypersensitivity reactions are characterised by prompt activation of mast cells and other immune cells, with notable and immediate secretion of water and inflammatory mediators into the intestinal lumen. Analysis of the profile of markers released into the jejunum after food provocation may be useful for the objective diagnosis of food allergy.