What causes tree nut allergies?

Tree nut allergies are caused by an inappropriate reaction of the immune system to the proteins found in tree nuts. Normally, the immune system targets and attacks pathogens like viruses and bacteria but in the case of food allergies, the immune system identifies a certain food as an “invader” and launches an immune response against it.

This breakdown of immune tolerance is primarily driven by T helper 2 cells and often includes the production of food-specific IgE antibodies, all of which lead to a cascade of immune responses (like the activation of mast cells and release of cytokines) that cause allergic symptoms. Why the immune system reacts abnormally to certain foods in some people is not fully understood.^[1]