Food allergy is an immune system over-reaction to a food protein. The cause of this over-reaction has remained a mystery until now.

The aim was to identify the route that proteins from digested peanuts take to the lymphoid tissue of the gut where immune responses start”.



Firstly, using a digestion model, the research team found that digestion through the stomach and small intestine produces large amounts of soluble protein and intact protein bodies – large particle-like structures. Secondly, by labelling them with gold, Dr Nicoletti found that peanut proteins are delivered at high speed through the gut via M-cells.



M-cells are effective at rapidly delivering foreign bodies, including proteins, to defence cells. Protein bodies hitching a ride with M-cells are therefore likely to trigger defence cells into action. “Peanut proteins are delivered quickly, in large amounts and in highly immunogenic form to immune cells”, said Dr Nicoletti. “This may be important in explaining strong allergic reactions to peanuts”.



Peanuts frequently cause severe reactions, including potentially lethal anaphylaxis. Peanut allergy can be so severe that only very tiny amounts can be enough to trigger a response.



The neighbouring cells to M-cells are enterocytes. Proteins delivered via these cells are processed to form peptides, and when presented to the immune system are likely to induce tolerance. “This research shows that antigens have the ability to dictate the route of transport, and in doing so the type of immune response that follows”, said Dr Nicoletti.



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