Type I Hypersensitivity Reactions

Question 1

What are Hypersensitivity reactions?

Answer 1

Immune reactions that are excessive or harmful

Question 2

How many types of Hypersensitivity reactions are there?

Answer 2

4 (I-IV)

Question 3

When will you recognize Type I reactions?

Answer 3

ON SIGHT

Question 4

What are the most common Type I reactions?

Answer 4

Seasonal and Food Allergies
Asthma
Anaphylaxis, Angioedema, Hives (urticaria)

Question 5

What are the most common Type I reactions?

Answer 5

Seasonal and Food Allergies
Asthma
Anaphylaxis, Angioedema, Hives (urticaria)

Question 6

Describe the setup before a Type I reaction will take place

Answer 6

• DCs present Ag to naive T cells
• T cells differentiate into Th2 cells
• Th2 cells cause the B cells to switch to IgE
• Mast cells prepare by binding IgE to their FcER1

Question 7

For a Type I reaction, what occurs after the DC presents the Antigen to a naive T cell?

Answer 7

T cell turns into a Th2 cell

Question 8

For a Type I reaction, what occurs after a Th2 cell is created?

Answer 8

B cells class switch to IgE

Question 9

For a Type I reaction, what occurs after IgE is made?

Answer 9

Mast cells bind IgE to their receptor FcER1

Question 10

What cytokine helps B cells class switch to IgE?

Answer 10

IL-4

Question 11

What cytokine helps enhance IgE production?

Answer 11

IL-13

Question 12

What cytokine activates Eosinophils?

Answer 12

IL-5

Question 13

What occurs for a Type I reaction to take place?

Answer 13

REPEAT EXPOSURE TO ANTIGEN

Question 14

What occurs upon repeat exposure to the antigen?

Answer 14

Mast cells degranulate

Question 15

The immediate reaction for Type I occurs in minutes. What is specifically released from the mast cells in this phase?

Answer 15

Histamine
Leukotrienes (B4, C4, D4)
Prostaglandin D2
Platelet Activating factor

Question 16

Result of the immediate reaction for Type I?

Answer 16

Vasodilation and Increased vascular permeability

Smooth muscle contraction

Question 17

The immediate reaction for Type I occurs in minutes. What is specifically released from the mast cells in this phase?

Answer 17

Histamine
Leukotrienes (B4, C4, D4)
Prostaglandin D2
Platelet Activating factor

Question 18

The late phase for Type I occurs 2-24 hours after initial exposure. What is specifically released from the mast cells in this phase?

Answer 18

Cytokines and chemokines

Question 19

When cytokines and chemokines are released during the late phase, what do they do?

Answer 19

Recruit leukocytes - eosinophils, basophils, neutrophils

Question 20

When cytokines and chemokines are released during the late phase, what do they do?

Answer 20

Recruit leukocytes - eosinophils, basophils, neutrophils

Question 21

Result of the late phase for Type I?

Answer 21

Epithelial damage

Bronchospasm

Question 22

What causes Eosinophilic Esophagitis?

Answer 22

Food antigens

Question 23

Symptoms and age group of those affected with Eosinophilic Esophagitis?

Answer 23

Children

= Dysphagia, weight loss, hurts to swallow

Question 24

Treatment cascade for Type I reactions?

Answer 24

Diagnose that a reaction is occurring
Treat - block histamine or airway support
Identify allergen

Question 25

Describe the skin-prick test

Answer 25

• Inject allergen
• IgE that is bound to mast cells binds allergen
• IgE cross links to activate mast cells
  = Vasodilation and increased permeability
  = = Redness and swelling at site of injection