Hypersensitivity Reactions Flashcards

Covering types 1-4 of hypersensitivity

1
Q

Immunologically-mediated tissue injury leads to…

A

hypersensitivity reactions

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2
Q

What are the four classes of hypersensitivity reactions?

A
  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)
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3
Q

Type I hypersensitivity is mediated by which antibody?

A

IgE

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4
Q

IgE antibodies bind… causing…

A

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

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5
Q

Type I hypersensitivity involves a release of various mediators including…

A

histamine (vasodilator)

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6
Q

Describe the effects of histamine in type I hypersensitivity

A
  • Leads to vascular leakage, especially venules
  • The arteriolar dilation leads to hypotension
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7
Q

What are some examples of type I hypersensitivity?

A

Allergies, anaphylactic reactions

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8
Q

What is one treatment for type I hypersensitivity?

A

Allergen immunotherapy to reduce specific IgE levels

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9
Q

type I hypersensitivity

With more IgG, there is less…

A

IgE

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10
Q

type I hypersensitivity

What is the effect of IgE on a mast cell?

A

Sensitizes the mast cell to an antigen by binding to it

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11
Q

type I hypersensitivity

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

A

Increased IgE production

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12
Q

type I hypersensitivity

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

A

Binding to IgE and degranulation of mast cells

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13
Q

type I hypersensitivity

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

A
  • Histamine
  • Leukotrienes
  • Eosinophil chemotactic factor
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14
Q

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

A

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

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15
Q

type II hypersensitivity

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

A

Ab production

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16
Q

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

A

complement activation and tissue damage

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17
Q

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

A

Cells are killed

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18
Q

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

A

Goodpasture syndrome

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19
Q

type II hypersensitivity

What is Goodpasture syndrome?

A

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

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20
Q

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

A
  • Grave disease
  • Myasthenia gravis
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21
Q

type II hypersensitivity

What is Grave disease?

A
  • Autoimmune thyroiditis with hyperthyroid
  • Anti-TSH-receptor antibodies present
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22
Q

Grave disease

TSH normally functions to…

A

increase T3 and T4

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23
Q

type II hypersensitivity

Describe myasthenia gravis

A
  • Anti-acetylcholine receptor antibodies
  • Acetylcholine can’t bind
  • No contraction possible leads to paralysis
24
Q

type II hypersensitivity

Describe Hashimoto’s thyroiditis

A
  • Antibodies against thyroid
  • Hypothyroidism
25
Q

type II hypersensitivity

What is erythroblastosis fetalis?

A

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

26
Q

type II hypersensitivity

What is autoimmune hemolytic anemia?

A

A hemolytic disease of a newborn where RBCs are attacked

27
Q

type II hypersensitivity

Describe hyperacute graft rejection

A

Preformed anti-graft antibodies in host

28
Q

type II hypersensitivity

Rheumatic fever involves antibodies for…

A

streptococcal M proteins

29
Q

Type III hypersensitivity is ___ mediated

A

immune complex

30
Q

type III hypersensitivity

Antibodies ___ bind to ___ forming “immune” complexes

A

IgG and IgM bind to circulating antigens

31
Q

type III hypersensitivity

Immune complexes become extremely large meshworks with…

A

Ag bridges

32
Q

type III hypersensitivity

___ system is implicated in normal clearance of immune complexes

A

Complement

33
Q

In type III hypersensitivity, antibodies are formed against…

A

circulating antigens

34
Q

type III hypersensitivity

Ag/AB complexes circulate and are deposited in…

A

tissues

35
Q

type III hypersensitivity

Deposited complexes (Ag/AB) induce…

A

an inflammatory response (activates complement system, attracts luekocytes)

36
Q

What is a local example of an immune complex disease?

A

Arthus reaction

37
Q

type III hypersensitivity

What is Arthus reaction?

A

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

38
Q

What is a systemic example of an immune complex disease?

A

Lupus

39
Q

type III hypersensitivity

What is lupus?

A

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

40
Q

type III hypersensitivity

What is Henoch-Schonlein Purpura?

A

Most common childhood vasculitis involving a rash on buttocks and thighs

41
Q

type III hypersensitivity

Glomerulonephritis affects…

A

kidneys only

42
Q

Type IV hypersensitivity is ___ mediated or ___

A

T-cell-mediated or delayed type

43
Q

type IV hypersensitivity

Does an antigen-elicited immune reaction require an antibody?

A

No antibody required

44
Q

type IV hypersensitivity

With delayed hypersensitivity, foreign antigens elicit…

A

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

45
Q

type IV hypersensitivity

Cytokines cause activation of…

A

macrophages and lymphocytes

46
Q

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

A

24-48 hours after

47
Q

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

A

Within days to several weeks after introduction of antigen

48
Q

Type IV hypersensitivity reaction is mediated by which cells specifically?

A

CD4+ T cells aka T-DTH

49
Q

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

A

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

50
Q

Type IV hypersensitivity requires what sort of exposure to antigens?

A

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

51
Q

Reactions to poison ivy and poison sumac are examples of…

A

cutaneous sensitivity, type IV hypersensitivity reaction

52
Q

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

A

type IV hypersensitivity

53
Q

Granulomatous disease is an example of…

A

type IV hypersensitivity

54
Q

Sarcoidosis and Crohn’s disease are both examples of…

A

type IV hypersensitivity

55
Q

Spirochete diseases, especially treponema pallidum, are examples of…

A

type IV hypersensitivity

56
Q

Deep fungal infections such as histoplasmosis are examples of…

A

type IV hypersensitivity