IMMUNOLOGY

Detailed explanation-1: -When a harmless substance such as dust, mold, or pollen is encountered by a person who is allergic to that substance, the immune system may over react by producing antibodies that “attack” the allergen. The can cause wheezing, itching, runny nose, watery or itchy eyes, and other symptoms.

Detailed explanation-2: -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-3: -Additional exposure to the sensitizing allergen leads to the development of an allergic reaction through the release of histamine and other chemicals from mast cells.

Detailed explanation-4: -An allergy may be a damaging immune response by the body to a substance, especially pollen, fur, a particular food, or dust, to which it has become hypersensitive.