PATHOLOGY

Detailed explanation-1: -Hypersensitivity reactions are exaggerated or inappropriate immunologic responses occurring in response to an antigen or allergen.

Detailed explanation-2: -Type I hypersensitivities include atopic diseases, which are an exaggerated IgE mediated immune responses (i.e., allergic: asthma, rhinitis, conjunctivitis, and dermatitis), and allergic diseases, which are immune responses to foreign allergens (i.e., anaphylaxis, urticaria, angioedema, food, and drug allergies).

Detailed explanation-3: -An overactive immune system If you are born with certain genes, your immune system may react to substances in the environment that are normally harmless. These substances are called allergens. Having an allergic reaction is the most common example of an overactive immune system.

Detailed explanation-4: -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-5: -An antibody-mediated hypersensitivity reaction is an exaggerated immune reaction due to specific binding of antibody and the type of molecule involved (i.e., antigen).