Mechanism: Type I reactions are mediated by proteins called IgE antibodies produced by the immune system. Antigen reacts with IgE bound to surface of basophils or tissue mast cells, causing degranulation with release of histamine and other substances, many of which are vasoactive, smooth muscle spasm inducing, or chemotactic
These are produced in response to the allergens such as pollen, animal dander or dust mites, or even certain foods. This causes the release of histamine and other chemicals causing inflammation and swelling. Examples of type I allergic reactions include
Anaphylaxis is the most severe form and is a medical emergency because it can lead to a sudden, life-threatening respiratory failure.
People with anaphylaxis have extreme difficulty in breathing, swelling, low blood pressure, bluish skin and shock.