Hypersensitivity Reactions

These flashcards cover key vocabulary and concepts related to hypersensitivity reactions, including their definitions and mechanisms.

Hypersensitivity Reactions

Immune responses that occur upon re-exposure to innocuous environmental antigens, causing inflammation and tissue damage.

Allergen

An antigen that causes an allergic reaction, often an innocuous protein.

Allergy

A state of hypersensitivity to normally innocuous environmental antigens, which can involve antibodies or T cells.

Type I hypersensitivity

Reactions caused by the binding of an allergen to IgE on mast cells, resulting in degranulation and release of inflammatory mediators.

IgE

An antibody that binds to allergens and is responsible for triggering Type I hypersensitivity reactions.

Degranulation

The process by which mast cells release inflammatory mediators, especially histamine, upon activation.

Eosinophils

White blood cells involved in allergic responses and defense against parasites, releasing inflammatory mediators.

Basophils

Granulocytes that play a role in allergic responses and are recruited to sites of allergic reactions.

Type II hypersensitivity

Reactions caused by antibody-dependent cytotoxicity, involving B cells producing IgG against cell-surface antigens.

Type III hypersensitivity

Reactions due to immune complexes formed by soluble proteins binding to IgG, resulting in tissue damage.

Type IV hypersensitivity

Reactions mediated by antigen-specific T cells, also known as delayed type hypersensitivity.

Stimulatory hypersensitivity

A type of hypersensitivity where antibodies act as agonists for cell surface receptors.

Innate hypersensitivity

Hypersensitivity reactions related to the innate immune system, such as excessive activation of pattern recognition receptors (PRRs).

Anaphylaxis

A severe, life-threatening allergic reaction characterized by intense bronchoconstriction and vasodilation.

Atopic allergy

The inappropriate generation of IgE against external allergens, leading to allergic conditions such as asthma and eczema.