Background: Manifestations of food allergies vary among patients, being the most common gastrointestinal, skin and respiratory symptoms. This study aimed to identify and characterize polyp Th2 cells as a critical component of the allergic reaction. We previously characterized colorectal polyps in patients sensitized to food allergens as inflammatory, with a Type 2-dominated stroma, with elevated IL-13, IL-4 and locally synthesized IgE. Methods: We isolated milk-specific T cells from tissue and blood of food-sensitized patients (n=10) and obtained cell lines and cell clones. Proliferation, specificity, cytokine secretion, gut homing markers and TCR nature were analyzed after antigen recall; CCL25 was assessed in polyps and surrounding tissue. Results: Lamina propria and peripheral T cells responded similarly to cow´s milk proteins, showing similar cell proliferation index and Th2 cytokine release in vitro. All CD4 + T cells expressed the membrane T αβ receptor and secreted higher IL-13 amounts than unstimulated cells, whereas IFN-γ secretion remained unchanged. Remarkably, the gut homing chemokine receptor CCR9 was augmented in cow’s milk-specific peripheral and lamina propria T cells, and CCL25 was found to be expressed in the inflammatory polyp tissue and not in the adjacent mucosa. Conclusion: We isolated and characterized cow´s milk-specific lamina propria CD4 + TCRαβ + Th2 cells from colonic inflammatory polyps. The CCR9 expression on polyp cells and the increased production of tissue CCL25 might facilitate T cells’ recruitment, which are key players in the allergic reaction to promote local IgE synthesis. Our findings may be critical to proposing rational and novel T cell-targeted immunotherapies.

Background: Pollen-allergy is common in Austria. The present study investigated if the use of major pollen-allergens on top of extract-based diagnosis may improve the diagnostic accuracy and if this additional knowledge helps to identify patients eligible for allergen-specific immunotherapy (AIT). Methods: In this retrospective database analysis patients sensitized to a grass, birch, ash-tree, mugwort or ragweed were investigated and results of pollen extracts compared to the respective major allergens (Phl p 1, Bet v 1, Ole e 1, Art v 1, Amb a 1) were assessed. Furthermore, extract- and MD- results of patients double-sensitized to both tree-extracts or both weed-extracts were compared. In patients with discrepant results, their charts were reviewed to define if this difference was clinically relevant in regard to their doctors´ AIT-decision. Results: 4234 patients (age 1.2-89.7yrs) could be included in the analyses. There was high agreement between extract-based IgE results and major allergens concerning single-sensitization to grass/Phl p 1+5 (94.4%), birch/Bet v 1 (94.4%), and ash-tree/Ole e 1 (82.9%), with lower agreement between mugwort/Art v 1 (64.1%) and ragweed/Amb a 1 (73.8%). Among patients double-sensitized to both tree pollen extracts only 76% were also sensitized to both major allergens (Bet v 1 and Ole e 1) and therefore suitable for AIT. In patients double-sensitized to both weeds, only 25% were also sensitized to both major allergens (Art v 1 and Amb a 1), 46.2% of mugwort extract positive patients tested negative for Art v 1. Of these patients, 41.3% were recommended a ragweed AIT as their Amb a 1 results were positive. Conclusion: MD can improve diagnostic accuracy in patients with pollen-allergy and should be implemented in standard clinical care, especially when double-sensitization to allergens of plants with overlapping pollen seasons cannot be clearly discerned by patients´ symptoms alone.