IgE Triggers Mast Cells and Basophils Immediate or Type 1 patterns of allergy can largely be attributed to IgE and a sub-population of immune cells, the mast cells and basophils. These cells degranulate if sufficient antigen reacts with IgE antibodies which act as receptors on the cell's surface. An inherited tendency to make excessive amounts of IgE antibody is one characteristic of atopic individuals. The most explosive, immediate, and obvious allergic reactions begin with allergens attaching to basophil and mast cells triggering their degranulation. Allergens meet reactive cells just under the surface of the skin, respiratory, gastrointestinal and genitourinary tracts.
Mast cells release three sets of mediators with dramatic, immediate, local and systemic effects.
The big players are histamine, prostaglandins, and cytokines, including leukotrienes B4, C4, D4, E4. All are bronchoconstrictors and increase permeability of blood vessels as in anaphylaxis and asthma. Three factors recruit and activate other groups of cells which play a major role in extending the immune response for hours to days. Eosinophils release major basic protein which is damaging to cells. The news to many physicians was that there was more to allergy than immediate reactions mediated by histamine.