Allergy and Hypersensitivity

Question 1

Allergy

Answer 1

An exaggerated immune response to harmless environmental substances (allergens).

Question 2

Hypersensitivity

Answer 2

An abnormal immune reaction to a substance that causes tissue damage.

Question 3

Type I hypersensitivity

Answer 3

Immediate hypersensitivity (e.g.; hay fever; anaphylaxis); caused by IgE binding to mast cells and basophils; leading to degranulation and release of histamine.

Question 4

IgE-mediated hypersensitivity

Answer 4

Involves IgE antibodies that bind to allergens and trigger the release of histamines from mast cells.

Question 5

Anaphylaxis

Answer 5

A severe; systemic allergic reaction that can cause airway constriction; shock; and death without prompt treatment.

Question 6

Histamine in allergic reactions

Answer 6

Released by mast cells; histamine causes vasodilation; increased permeability; and smooth muscle contraction.

Question 7

Type II hypersensitivity

Answer 7

Cytotoxic hypersensitivity; where IgG or IgM antibodies target cells for destruction via complement activation or phagocytosis (e.g.; hemolytic anemia).

Question 8

Type III hypersensitivity

Answer 8

Immune complex-mediated hypersensitivity; where antigen-antibody complexes deposit in tissues and cause inflammation (e.g.; systemic lupus erythematosus).

Question 9

Type IV hypersensitivity

Answer 9

Delayed-type hypersensitivity (e.g.; contact dermatitis); mediated by T cells rather than antibodies; with symptoms appearing hours to days after exposure.

Question 10

Allergic rhinitis

Answer 10

An allergy-triggered inflammation of the nasal airways; often caused by pollen; dust mites; or animal dander.

Question 11

Allergic asthma

Answer 11

An allergic reaction in the lungs causing bronchoconstriction; inflammation; and difficulty breathing.

Question 12

Eosinophils in allergic reactions

Answer 12

Play a role in the inflammatory response and tissue damage; especially in asthma and other allergic conditions.

Question 13

Mast cells

Answer 13

Immune cells that release histamine and other mediators upon activation by IgE or allergens; playing a central role in allergic reactions.

Question 14

Basophils

Answer 14

White blood cells that release histamine and other inflammatory mediators during allergic reactions.

Question 15

Allergen

Answer 15

A substance that triggers an allergic reaction. Common allergens include pollen; dust mites; mold; and pet dander.

Question 16

Antihistamines

Answer 16

Drugs used to block the effects of histamine; providing relief from allergy symptoms like sneezing; itching; and swelling.

Question 17

Desensitization (allergen immunotherapy)

Answer 17

A treatment for allergies where patients are exposed to gradually increasing amounts of an allergen to reduce their sensitivity.

Question 18

Corticosteroids in allergy treatment

Answer 18

Anti-inflammatory drugs that reduce swelling; redness; and other symptoms of allergic reactions.

Question 19

Atopy

Answer 19

A genetic predisposition to develop allergic diseases such as asthma; hay fever; or eczema.

Question 20

Food allergies

Answer 20

Hypersensitivity reactions to certain foods; such as peanuts or shellfish; that can lead to anaphylaxis in severe cases.

Question 21

Anaphylactic shock

Answer 21

A life-threatening allergic reaction that can lead to low blood pressure; difficulty breathing; and organ failure.

Question 22

Late-phase allergic reaction

Answer 22

A prolonged allergic response involving T cells; eosinophils; and other inflammatory cells that cause tissue damage.

Question 23

Allergic contact dermatitis

Answer 23

A Type IV hypersensitivity reaction where T cells react to allergens like poison ivy; resulting in itching; redness; and swelling.

Question 24

Angioedema

Answer 24

Swelling of the deeper layers of the skin; often caused by an allergic reaction; particularly to food or insect stings.

Question 25

IgG in hypersensitivity

Answer 25

IgG antibodies can participate in Type II hypersensitivity by binding to cell surface antigens; leading to complement activation and cell destruction.

Question 26

Allergy skin tests

Answer 26

Tests that involve introducing small amounts of allergens under the skin to see if there is an allergic response; helping to diagnose specific allergies.

Question 27

Serum sickness

Answer 27

A Type III hypersensitivity reaction to certain medications or antiserum; leading to fever; rash; and joint pain.

Question 28

T-cell-mediated allergy

Answer 28

In Type IV hypersensitivity; T cells are activated by allergens; leading to inflammation and tissue damage.

Question 29

Autoimmune diseases as hypersensitivity

Answer 29

Some autoimmune diseases (e.g.; lupus) are considered Type III hypersensitivity reactions due to the formation of immune complexes.

Question 30

Epinephrine in anaphylaxis treatment

Answer 30

A fast-acting treatment that constricts blood vessels and dilates airways; helping to reverse the symptoms of severe allergic reactions.

Question 31

Chronic allergic diseases

Answer 31

Conditions like asthma and rhinitis that result from prolonged allergic responses and inflammation.