ANATOMY

Detailed explanation-1: -Allergic reactions (hypersensitivity reactions) are inappropriate responses of the immune system to a normally harmless substance. Usually, allergies cause sneezing, watery and itchy eyes, a runny nose, itchy skin, and rash. Some allergic reactions, called anaphylactic reactions.

Detailed explanation-2: -Anaphylaxis. Anaphylaxis is a medical emergency as it can lead to acute, life-threatening respiratory failure. It is an IgE-mediated process. It is the most severe form of an allergic reaction, where mast cells suddenly release a large amount of histamine and later on leukotrienes.

Detailed explanation-3: -Allergy is often equated with type I hypersensitivity (immediate-type hypersensitivity reactions mediated by IgE), and will be used in this sense here.

Detailed explanation-4: -Summary. A hypersensitivity reaction occurs when the body produces an unnecessary and undesirable immune response following exposure to a certain antigen. Many people refer to hypersensitivity as a form of allergy.

Detailed explanation-5: -Type I: reaction mediated by IgE antibodies. Type II: cytotoxic reaction mediated by IgG or IgM antibodies. Type III: reaction mediated by immune complexes. Type IV: delayed reaction mediated by cellular response. 14-Aug-2022