Allergy and Hypersensitivity Flashcards
Allergy
An exaggerated immune response to harmless environmental substances (allergens).
Hypersensitivity
An abnormal immune reaction to a substance that causes tissue damage.
Type I hypersensitivity
Immediate hypersensitivity (e.g.; hay fever; anaphylaxis); caused by IgE binding to mast cells and basophils; leading to degranulation and release of histamine.
IgE-mediated hypersensitivity
Involves IgE antibodies that bind to allergens and trigger the release of histamines from mast cells.
Anaphylaxis
A severe; systemic allergic reaction that can cause airway constriction; shock; and death without prompt treatment.
Histamine in allergic reactions
Released by mast cells; histamine causes vasodilation; increased permeability; and smooth muscle contraction.
Type II hypersensitivity
Cytotoxic hypersensitivity; where IgG or IgM antibodies target cells for destruction via complement activation or phagocytosis (e.g.; hemolytic anemia).
Type III hypersensitivity
Immune complex-mediated hypersensitivity; where antigen-antibody complexes deposit in tissues and cause inflammation (e.g.; systemic lupus erythematosus).
Type IV hypersensitivity
Delayed-type hypersensitivity (e.g.; contact dermatitis); mediated by T cells rather than antibodies; with symptoms appearing hours to days after exposure.
Allergic rhinitis
An allergy-triggered inflammation of the nasal airways; often caused by pollen; dust mites; or animal dander.
Allergic asthma
An allergic reaction in the lungs causing bronchoconstriction; inflammation; and difficulty breathing.
Eosinophils in allergic reactions
Play a role in the inflammatory response and tissue damage; especially in asthma and other allergic conditions.
Mast cells
Immune cells that release histamine and other mediators upon activation by IgE or allergens; playing a central role in allergic reactions.
Basophils
White blood cells that release histamine and other inflammatory mediators during allergic reactions.
Allergen
A substance that triggers an allergic reaction. Common allergens include pollen; dust mites; mold; and pet dander.
Antihistamines
Drugs used to block the effects of histamine; providing relief from allergy symptoms like sneezing; itching; and swelling.
Desensitization (allergen immunotherapy)
A treatment for allergies where patients are exposed to gradually increasing amounts of an allergen to reduce their sensitivity.
Corticosteroids in allergy treatment
Anti-inflammatory drugs that reduce swelling; redness; and other symptoms of allergic reactions.
Atopy
A genetic predisposition to develop allergic diseases such as asthma; hay fever; or eczema.
Food allergies
Hypersensitivity reactions to certain foods; such as peanuts or shellfish; that can lead to anaphylaxis in severe cases.
Anaphylactic shock
A life-threatening allergic reaction that can lead to low blood pressure; difficulty breathing; and organ failure.
Late-phase allergic reaction
A prolonged allergic response involving T cells; eosinophils; and other inflammatory cells that cause tissue damage.
Allergic contact dermatitis
A Type IV hypersensitivity reaction where T cells react to allergens like poison ivy; resulting in itching; redness; and swelling.
Angioedema
Swelling of the deeper layers of the skin; often caused by an allergic reaction; particularly to food or insect stings.
IgG in hypersensitivity
IgG antibodies can participate in Type II hypersensitivity by binding to cell surface antigens; leading to complement activation and cell destruction.
Allergy skin tests
Tests that involve introducing small amounts of allergens under the skin to see if there is an allergic response; helping to diagnose specific allergies.
Serum sickness
A Type III hypersensitivity reaction to certain medications or antiserum; leading to fever; rash; and joint pain.
T-cell-mediated allergy
In Type IV hypersensitivity; T cells are activated by allergens; leading to inflammation and tissue damage.
Autoimmune diseases as hypersensitivity
Some autoimmune diseases (e.g.; lupus) are considered Type III hypersensitivity reactions due to the formation of immune complexes.
Epinephrine in anaphylaxis treatment
A fast-acting treatment that constricts blood vessels and dilates airways; helping to reverse the symptoms of severe allergic reactions.
Chronic allergic diseases
Conditions like asthma and rhinitis that result from prolonged allergic responses and inflammation.
