Aim of the study is to improve the diagnosis of food allergy and hypersensitivity. Intestinal homogenates will be used to determine total IgE, specific IgE, tryptase, histamine and inflammation parameters (IFNgamma, TNFalpha). These data will be correlated with serum values and disease status. In addition, organoids from duodenal tissue will be isolated and cultured in vitro and stimulated with the major food allergens. The gene and protein expression will be checked to identify relevant biomarkers.

Food intolerances (FI) show an increasing prevalence and represent a particular challenge in clinical practice. The symptoms of a predominantly gastrointestinally mediated food allergy (FA) are similar to the symptoms of other FI (e.g. carbohydrate malabsorption, gluten sensitivity, histamine intolerance, irritable bowel syndrome), so that diagnosis is difficult and often delayed.

Well-evaluated methods for the clarification of an allergic disease are serological screening (IgE against food products or other cross-reacting allergens) and skin prick tests. However, these methodes have their limitations in the diagnosis of seronegative or mainly gastrointestinal-mediated FI. Patients often associate the consumption of certain foods with the clinical symptoms, which often leads to strict self-imposed elimination diets, but rarely to the correct identification of the triggering food.

In a pilot study, the investigators showed that patients with gastrointestinal FI have elevated mucosal IgE levels and TNF using homogenates from intestinal biopsies. Another patient subgroup could be identified that showed low allergic parameters (low mucosal IgE, low TNF) but high mucosal interferon levels, indicating a non-specific inflammation.

In this study, mucosal IgE, tryptase, histamine, IL4, and inflammatory parameters (e.g. TNF, IFN) from different areas of the gastrointestinal tract will be determined in a larger collective. Furthermore, organoids are cultured in vitro from duodenal tissue samples, incubated with blood cells and stimulated with food allergens. The titres of specific IgE from the mucosal homogenates will be correlated with serum levels and organoid stimulation results to identify relevant biomarkers. Microbiome and metabolome analyses will provide information about the intestinal flora in FI.

Inclusion Criteria:

• informed consent
• patients with suspected food allergy or hypersensitivity
• healthy controls with indications for endoscopic diagnostics, e.g. tumour history within the family, exclusion of gastritis

Exclusion Criteria:

• pregnant person