Hypersensitivity Reactions

Question 1

Immunologically-mediated tissue injury leads to…

Answer 1

hypersensitivity reactions

Question 2

What are the four classes of hypersensitivity reactions?

Answer 2

1. Type I Immediate Type (IgE mediated/anaphylactic)
2. Type II Cytotoxic
3. Type III Immune Complex Mediated
4. Type IV Delayed Type (T cell mediated)

Question 3

Type I hypersensitivity is mediated by which antibody?

Answer 3

IgE

Question 4

IgE antibodies bind… causing…

Answer 4

bind mast cells, basophils, cross link IgE receptors causing degranulation

Question 5

Type I hypersensitivity involves a release of various mediators including…

Answer 5

histamine (vasodilator)

Question 6

Describe the effects of histamine in type I hypersensitivity

Answer 6

• Leads to vascular leakage, especially venules
• The arteriolar dilation leads to hypotension

Question 7

What are some examples of type I hypersensitivity?

Answer 7

Allergies, anaphylactic reactions

Question 8

What is one treatment for type I hypersensitivity?

Answer 8

Allergen immunotherapy to reduce specific IgE levels

Question 9

type I hypersensitivity

With more IgG, there is less…

Answer 9

IgE

Question 10

type I hypersensitivity

What is the effect of IgE on a mast cell?

Answer 10

Sensitizes the mast cell to an antigen by binding to it

Question 11

type I hypersensitivity

Upon initial exposure to an antigen, what is the effect on IgE?

Answer 11

Increased IgE production

Question 12

type I hypersensitivity

Upon subsequent exposure to an antigen, what is the effect on IgE?

Answer 12

Binding to IgE and degranulation of mast cells

Question 13

type I hypersensitivity

As IgE binds to mast cells, leading to degranulation, what is released?

Answer 13

• Histamine
• Leukotrienes
• Eosinophil chemotactic factor

Question 14

In type II hypersensitivity, which antibodies will bind to what?

Answer 14

IgG and IgM bind to fixed (not soluble) target antigens (on a host cell surface)

Question 15

type II hypersensitivity

Initial sensitization, or cross reaction with infectious agent leads to…

Answer 15

Ab production

Question 16

In type II hypersensitivity, the antibodies bind to “self” antigens and trigger…

Answer 16

complement activation and tissue damage

Question 17

What does it mean when type II hypersensitivity is called cytotoxic?

Answer 17

Cells are killed

Question 18

What is an example of a syndrome involving type II hypersensitivity?

Answer 18

Goodpasture syndrome

Question 19

type II hypersensitivity

What is Goodpasture syndrome?

Answer 19

Autoimmune disease where antibodies are made against glomerular basement membrane destroying kidneys

Question 20

What are two type II hypersensitivity reactions that do not lead to death but can alter normal physiology?

Answer 20

• Grave disease
• Myasthenia gravis

Question 21

type II hypersensitivity

What is Grave disease?

Answer 21

• Autoimmune thyroiditis with hyperthyroid
• Anti-TSH-receptor antibodies present

Question 22

Grave disease

TSH normally functions to…

Answer 22

increase T3 and T4

Question 23

type II hypersensitivity

Describe myasthenia gravis

Answer 23

• Anti-acetylcholine receptor antibodies
• Acetylcholine can’t bind
• No contraction possible leads to paralysis

Question 24

type II hypersensitivity

Describe Hashimoto’s thyroiditis

Answer 24

• Antibodies against thyroid
• Hypothyroidism

Question 25

#type II hypersensitivity What is erythroblastosis fetalis?

Answer 25

Blood group antibodies involved: Rh disease where mom's blood mixes with fetal blood

Question 26

#type II hypersensitivity What is autoimmune hemolytic anemia?

Answer 26

A hemolytic disease of a newborn where RBCs are attacked

Question 27

#type II hypersensitivity Describe hyperacute graft rejection

Answer 27

Preformed anti-graft antibodies in host

Question 28

#type II hypersensitivity Rheumatic fever involves antibodies for...

Answer 28

streptococcal M proteins

Question 29

Type III hypersensitivity is ___ mediated

Answer 29

immune complex

Question 30

#type III hypersensitivity Antibodies ___ bind to ___ forming "immune" complexes

Answer 30

IgG and IgM bind to circulating antigens

Question 31

#type III hypersensitivity Immune complexes become extremely large meshworks with...

Answer 31

Ag bridges

Question 32

#type III hypersensitivity ___ system is implicated in normal clearance of immune complexes

Answer 32

Complement

Question 33

In type III hypersensitivity, antibodies are formed against...

Answer 33

circulating antigens

Question 34

#type III hypersensitivity Ag/AB complexes circulate and are deposited in...

Answer 34

tissues

Question 35

#type III hypersensitivity Deposited complexes (Ag/AB) induce...

Answer 35

an inflammatory response (activates complement system, attracts luekocytes)

Question 36

What is a local example of an immune complex disease?

Answer 36

Arthus reaction

Question 37

#type III hypersensitivity What is Arthus reaction?

Answer 37

Toxoid of injection causes localized type III hypersensitivity increasing WBC and Ab to area and redness/soreness at injection site

Question 38

What is a systemic example of an immune complex disease?

Answer 38

Lupus

Question 39

#type III hypersensitivity What is lupus?

Answer 39

Antibodies involved in a butterfly rash on face, rash in kidneys, liver, and joints

Question 40

#type III hypersensitivity What is Henoch-Schonlein Purpura?

Answer 40

Most common childhood vasculitis involving a rash on buttocks and thighs

Question 41

#type III hypersensitivity Glomerulonephritis affects...

Answer 41

kidneys only

Question 42

Type IV hypersensitivity is ___ mediated or ___

Answer 42

T-cell-mediated or delayed type

Question 43

#type IV hypersensitivity Does an antigen-elicited immune reaction require an antibody?

Answer 43

No antibody required

Question 44

#type IV hypersensitivity With delayed hypersensitivity, foreign antigens elicit...

Answer 44

cytokine release (IL-1, IL-6, IL-12) by T-helper cell

Question 45

#type IV hypersensitivity Cytokines cause activation of...

Answer 45

macrophages and lymphocytes

Question 46

At what point will a type IV hypersensitivity reaction occur after exposure to an antigen?

Answer 46

24-48 hours after

Question 47

At what point will a type IV hypersensitivity reaction damage tissues?

Answer 47

Within days to several weeks after introduction of antigen

Question 48

Type IV hypersensitivity reaction is mediated by which cells specifically?

Answer 48

CD4+ T cells aka T-DTH

Question 49

Type IV hypersensitivity requires which cells (besides T cells)?

Answer 49

Intact antigen presenting cells, including Langerhan's cells of skin

Question 50

Type IV hypersensitivity requires what sort of exposure to antigens?

Answer 50

At least two exposures to the antigen: first for priming, second to give DTH

Question 51

Reactions to poison ivy and poison sumac are examples of...

Answer 51

cutaneous sensitivity, type IV hypersensitivity reaction

Question 52

Allergic sensitivities such as to cosmetics and detergents are examples of...

Answer 52

type IV hypersensitivity

Question 53

Granulomatous disease is an example of...

Answer 53

type IV hypersensitivity

Question 54

Sarcoidosis and Crohn's disease are both examples of...

Answer 54

type IV hypersensitivity

Question 55

Spirochete diseases, especially treponema pallidum, are examples of...

Answer 55

type IV hypersensitivity

Question 56

Deep fungal infections such as histoplasmosis are examples of...

Answer 56

type IV hypersensitivity