Immediate hypersensitivity

Question 1

What is immediate hypersensitivity?

Answer 1

A type I hypersensitivity reaction caused by IgE production and mast cell activation

Question 2

What is atopy?

Answer 2

A genetic predisposition to produce IgE antibodies in response to environmental allergens and develop strong hypersensitivity reactions

Question 3

What are common IgE-mediated allergic diseases?

Answer 3

Hay fever asthma eczema urticaria and allergic conjunctivitis

Question 4

What is asthma in the context of hypersensitivity?

Answer 4

An immediate hypersensitivity reaction in the lungs causing reversible airway obstruction and bronchial inflammation

Question 5

What are the symptoms of immediate hypersensitivity reactions?

Answer 5

Itchy skin rashes sneezing runny nose coughing wheezing red eyes swelling vomiting and diarrhea

Question 6

What is anaphylaxis?

Answer 6

A systemic immediate hypersensitivity reaction characterized by edema bronchoconstriction and hypotension

Question 7

What are common allergens in immediate hypersensitivity?

Answer 7

Dust mites tree and grass pollen food proteins such as peanuts animal dander and drugs

Question 8

What is the mechanism of immediate hypersensitivity?

Answer 8

Allergen exposure activates Th2 cells leading to B cell class switching to IgE IgE binds to mast cells and re-exposure triggers mast cell degranulation

Question 9

What cytokines are involved in IgE class switching?

Answer 9

IL4 and IL13 secreted by Th2 cells promote IgE production by B cells

Question 10

What mediators are released by mast cells in hypersensitivity?

Answer 10

Histamine platelet-activating factor leukotrienes prostaglandins and cytokines

Question 11

What are the early and late-phase responses in immediate hypersensitivity?

Answer 11

The early phase includes vasodilation edema and bronchospasm while the late phase involves cellular recruitment and inflammation

Question 12

What is the role of eosinophils in immediate hypersensitivity?

Answer 12

Eosinophils are recruited by IL5 and release toxic proteins such as major basic protein causing tissue damage

Question 13

What are the effects of histamine in hypersensitivity?

Answer 13

Bronchoconstriction vasodilation increased vascular permeability and stimulation of nerve endings causing itching

Question 14

What is the hygiene hypothesis in allergy development?

Answer 14

A lack of early exposure to infectious agents and parasites increases susceptibility to allergies by suppressing immune development

Question 15

How is anaphylaxis treated?

Answer 15

With adrenaline to reverse bronchoconstriction and vasodilation and antihistamines to block histamine receptors

Question 16

What are common treatments for asthma in hypersensitivity?

Answer 16

Corticosteroids to block inflammatory cytokines and sodium cromolyn to inhibit mast cell mediator release

Question 17

What is the role of Th2 cells in immediate hypersensitivity?

Answer 17

Th2 cells secrete IL4 IL13 IL5 and eotaxin promoting IgE production and eosinophil recruitment

Question 18

What is the genetic basis of atopy and IgE production?

Answer 18

Atopy is influenced by multiple genes including those encoding IL4 IL5 IL13 and Fc receptors

Question 19

What is the role of eotaxin in hypersensitivity?

Answer 19

Eotaxin attracts eosinophils to sites of inflammation

Question 20

How does dust mite allergen trigger hypersensitivity?

Answer 20

Dust mites produce proteins that can penetrate mucosal barriers and trigger IgE production

Question 21

What cytokines are involved in the late-phase response of hypersensitivity?

Answer 21

IL3 promotes mast cell proliferation TNF-alpha promotes inflammation and IL5 recruits eosinophils

Question 22

How do mast cells contribute to hypersensitivity reactions?

Answer 22

Mast cells release pre-formed mediators synthesize new mediators and produce cytokines during allergic responses

Question 23

What is the clinical course of immediate hypersensitivity reactions?

Answer 23

The immediate phase occurs within minutes while the late-phase reaction peaks hours after allergen exposure

Question 24

What is the focus of drug therapy for immediate hypersensitivity?

Answer 24

Blocking mast cell degranulation and the effects of mediators and cytokines