3.2.12 - Hypersensitivity

Question 1

What are the 4 types of hypersensitivity reactions?

Answer 1

Anaphylactic (type I)
Cytotoxic (type II)
Immune complex disease (type III)
Cell-mediated delayed hypersensitivity (type IV)

Question 2

Antibody class involved w/ anaphylactic reaction

Answer 2

IgE

Question 3

IgE half life

Answer 3

2-3 days

Question 4

IL-___ is important for class switching to IgE and IL-___ plays a role

Answer 4

IL-4
IL-13

Question 5

Where there’s less parasitic infections, there’s an increase/decrease of atopic allergic reactions

Answer 5

Increase

Question 6

Antigens are also referred to as

Answer 6

allergens

Question 7

3 common sources of allergens

Answer 7

Inhaled, injected, ingested

Question 8

Steps for IgE attaching to mast cells and basophils

Answer 8

• Allergen enters across mucosal membrane
• Cytotropic antibody (IgE) attaches to mast
  cell by Fc receptor
  Fab (antigen binding site)part’s ready
  to interact w/ allergen
• IgE remained attached for months on surface
  of mast cell, basophil, and activated
  eosinophils

Question 9

3 features of inhaled allergens that promote priming of the Th2 cells that drive the IgE response

Answer 9

Molecular type
low dose
high solubility

Question 10

IgE only remains isolated in blood for ___, but can remain attached to leukocytes for ___

Answer 10

few days

months

Question 11

Primary sensitization steps for anaphylactic reaction

Answer 11

1. exposure to pollen
2. extraction of antigen goes to mucosal surface
3. activation of Th2 cells
4. production of IgE and binding to mast cells

Question 12

IgE receptor

Answer 12

FcER1

Question 13

what else can interact w/ mast cells and cause release of mediators?

Answer 13

Anaphylatoxins (mainly C3a and C5a)

Question 14

What happens during the 2nd exposure to an allergen?

Answer 14

Mast cell coated in IgE antibody and allergen interacts w/ it and causes mediator release

Results in

Immediate hypersensitivity rxn within minutes (found in granules) AND late phase rxn within 2-8 hours (produced by mast cell in membrane)

Question 15

3 important mediators released by mast cells. What do each of them do?

Answer 15

Histamine
- capillary dilation
- increase vascular permeability
- Increase in mucous secretions

ECF-A

Leukotrienes
- similar properties to histamine

Question 16

The peak expiratory phase in response to inhaled allergen lasts for ___ min. The immediate response is due to ___ and the late response is due to ___

Answer 16

less than 30 min

Histamine
Leukotrine

Question 17

What are the 2 types of mast cells? Describe

Answer 17

Connective tissue - associated w/ blood
Mucosal - mucosal mast cells

Question 18

Mast cell’s release granules into what 3 locations? What is the effect in each of these?

Answer 18

GI tract
- diarrhea and vomiting

Airways
- expulsion of airway contents

Blood vessels
- Increased lymph flow

Question 19

What are the 2 types of allergic manifestations? What are examples of each? Which one has a genetic predisposition?

Answer 19

Atopic or local anaphylaxis
-ex: allergic rhinitis (hay fever)
- genetic predisposition

Systemic anaphylaxis
- ex: anaphylactic shock

Question 20

Acute vs. chronic response steps in asthma

Answer 20

acute
- Mucosal mast cell captures antigen → antibody response by producing IgE → inflammation causes SM to contract, increase in mucus secretion, increase in blood vessel permeability
- Cytokines produced bring in eosinophils
—Eosinophils can release their toxic substances

chronic
- Mediated by cytokines and eosinophil products

Question 21

systemic anaphylaxis results from ___. What is the local and systemic treatment?

Answer 21

systemic release of histamine and leukotrienes
- occurs in minutes

local = antihistamine
systemic = epinephrine

Question 22

Describe skin testing. Immediate response is due to ___ and response ~30 min is due to ___

Answer 22

Use to test allergies
Look for wheel (swelling) and flare (reddening around swelling)

leukotrienes
Histamine

Question 23

Describe hypo-sensitive treatment. You can also use a ___ antibody

Answer 23

• If you already know what you’re allergic to
• Treatment plan that gives you small amount of what you’re allergic to, but not enough to cause a response, only a small immune response
• IgE antibody starts to decrease over time
• IgG (blocking antibody) is produced over time in tissue fluid that has a chance to interact w/ allergen causing a problem before it can interact w/ IgE on mast cell

anti-IgE monoclonal antibody

Question 24

4 types of IgE mediated allergic reactions

Answer 24

Systemic anaphylaxis
Wheal and flare
allergic rhinitis
bronchial asthma

Question 25

Describe cytotoxic (type II) reaction

Answer 25

Antibody is directed against antigen on surface of cell End result = cell lysis through complement activation

Question 26

Examples of cytotoxic reaction

Answer 26

blood transfusion reaction drug reactions autoimmune hemolytic anemia antibody-dependent cell cytotoxicity (ADCC)

Question 27

Describe autoimmune hemolytic anemia

Answer 27

- occurs in cytotoxic reactions - Penicillin can either bind to bacterial transpeptidase and inactivate it OR can modify proteins on human RBC to create foreign epitopes (develops antibody against penicillin) ---End result can be hemolytic anemia

Question 28

Some drugs are ___ that can interact w/ surface proteins of cells and induce an antibody response

Answer 28

Haptens - don’t initiate immune response by themselves but if they react w/ decreased surface proteins they can trigger response

Question 29

Example of antibody-dependent cell cytotoxicity (ADCC)

Answer 29

Patient response to therapy directed against B cells employing an anti-CD20 antibody Rituximab → CD20 found on B cells as is CD19 - NK cell has receptor that binds to IgG antibody which causes NK to release (perforin and granzymes) - Retuximab is front line therapy in treating patients w/ B cell lymphomas

Question 30

Immune complex disease (type III) reaction is initiated by ___. Which can activate ___

Answer 30

antigen-antibody complexes which can induce an inflammatory response Complement system

Question 31

Example of a local response in immune complex disease. It's ___ induced. It results from and what causes it? Site of reaction?

Answer 31

Arthus reaction Locally previous exposure to antigen vaccine skin

Question 32

What are the 2 responses in immune complex disease?

Answer 32

Local and systemic response

Question 33

time of reaction for arthus reaction

Answer 33

5-6 hours after injection of antigen

Question 34

Describe systemic reaction in immune complex disease

Answer 34

Antigen-antibody complexes circulate throughout bloodstream and settling in organs, like the kidney, and initiation inflammatory response

Question 35

What do neutrophils try to do in the systemic reaction in the immune complex disease?

Answer 35

Neutrophils try to remove antigen-antibody complexes and destroy filtration system of kidney → renal failure if it goes on for too long

Question 36

If you have a large dose of drug that's not cleared right away, you have the ability to make ___, that then over time form ___

Answer 36

antibody antigen:antibody complexes

Question 37

autoimmune disease has continued production of

Answer 37

antigen:antibody complex