In the case of allergic reactions, what does the presence of an allergen specifically trigger?

In the context of allergic reactions, the presence of an allergen specifically triggers a severe immune response. When an individual who is sensitized to a particular allergen encounters that substance, their immune system misidentifies it as a threat. This triggers the production of Immunoglobulin E (IgE) antibodies, which bind to mast cells and basophils. Upon subsequent exposures to the same allergen, these cells release various chemicals, the most notable being histamine, leading to symptoms such as swelling, inflammation, and sometimes severe reactions like anaphylaxis.

The response can vary in severity among individuals, but it is characterized by an exaggerated immune reaction rather than a normal one. This is different from heightened sensitivity which might refer to any increased responsiveness, but in the case of allergies, it specifically involves an intense reaction that can have serious implications for health.