Mechanism behind anaphylaxis
The underlying mechanism which causes anaphylaxis to set in, can be immunologic or non-immunologic. Basically, both mechanisms involve various chemical mediators being released from inflammatory cells called mast cells and basophils. This release of chemicals can be mediated by antibody, Ig E. In this case, it is an immediate hypersensitivity reaction. In some cases, the allergen can directly cause the mast cells to burst and release chemicals without going through the immunologic pathway involving immunoglobulin Ig E.
Hypersensitivity implies that a reaction is stimulated in response to chemicals or agents that are usually tolerable. In such people, allergens trigger the immune system to operate a defense mechanism or allergy.