L:22 Hypersensitivity disorders Flashcards

1
Q

What is hypersensitivity

A

Exaggerated immune response harmful to organism itself

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2
Q

Classifications of the 4 types of hypersensitivity reactions

A

Antibody-mediated

Cell-mediated

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3
Q

Antibody mediated effector mechanisms

A

Type I, II, and III

Correspond to defenses against extracellular pathogens

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4
Q

Cell-mediated effector mechanisms

A

Type IV- corresponds to defense against intracellular pathogens

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5
Q

Clinical manifestation of Type I hypersensitivity caused by?

A

Mediators secreted by Mast cells

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6
Q

What type of hypersensitivity takes place when antibodies specific for the cell and tissue Ags cause injury or disease to the tissue?

A

Type II

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7
Q

What is it called when Abs bind to circulating Ags to form immune complexes, which deposit in vessels, leading to inflammation in the vessel walls (vasculitis)

A

Immune Complex diseases (type III hypersensitivity)

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8
Q

What is the cause of type IV hypersensitivity?

A

T cell mediated disease caused by inflammation caused by cytokines produced by CD4 Th1 and Th17, or killing of host by CD8 CTLs

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9
Q

Individuals with a strong propensity to develop allergic reaction is said to be what?

A

Atopic

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10
Q

Type I hypersensitivity rxn is controlled by the binding of what?

A

IgE Abs to FcĘR1 located on the membrane of MAST CELLS, BASOPHILS and EOSINOPHILS

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11
Q

Most IgE produced following initial contact with Ag becomes?

A

Fixed on the surface of mast cell and basophils..

Second contact with Ag, the Ag-Ab rxn occurs predominantly on mast cell and basophil membrane

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12
Q

Hallmarks of Immediate hypersensitivity

A

Acute vascular, smooth muscle reactions, and inflammation

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13
Q

What causes vascular dilation

A

Prostaglandins

Histamines

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14
Q

What causes prolonged smooth muscle contractions?

A

Leukotrienes

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15
Q

What induces local inflammation (the late phase rxn)

A

Cytokines

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16
Q

Time frame of immediate and late phase rxn

A

Immediate vascular and smooth muscle develops within minutes.
The late-phase rxn develops 2-4 hrs. later characterized by inflammation

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17
Q

reversible airway obstruction often caused by inflammatory mediators from mast cells

A

Asthma

*spasmatic contraction of smooth muscle surrounding bronchi decreasing lumen size and causing SOB

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18
Q

Anaphylaxis

A

Rapid release of vaso active amines from mast cells and basophils as well as cytokines. Results in smooth muscle contraction in vasculature and vasodilation of capillary epithelium. **BP decreases leading to vascular shock* contraction of smooth muscles in bronchi cause difficulty breathing

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19
Q

In type II hypersensitivity IgG and IgM activate what pathways?

A

Complement system by classical pathway. results in byproducts that recruit leukocytes to induce inflammation

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20
Q

Type II

What activates leukocytes resulting in pro-inflammatory response?

A

IgG antibodies binding to neutrophil and macrophage Fc receptors.

Reactive oxygen and lysosomal enzymes are released and damage adjacent tissue because Ab-Ag complexes are formed on target cell

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21
Q

Type III

Ab-Ag complexes deposit where?

A

blood vessels and other sites resulting in vascular inflammation, and subsequent ischemic damage to tissue

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22
Q

Type III

Major mechanism triggering tissue damage

A

Classical activation of complement

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23
Q

Type III

Tissue damage is mediated by?

A
  • Complement activation
  • Mast cell degranulation
  • Neutrophil chemotaxis
  • Inflammation caused by immune cells
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24
Q

Type IV (delayed type hypersensitivity DTH) is caused by?

A

Activation of Th1 cells

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25
Q

Unlike Type I, II, III passive transfer of type IV requires the transfer of ?

A

Antigen- specific TH1 clones

26
Q

What type of hypersensitivity is T cell mediated?

A

Type IV

27
Q

Tissue injury is caused by what in type IV

A

Inflammation induced by cytokines that are produced by CD4 Th1 cells and Th17
Inflammation associated with T-cell mediated disease is typically chronic

28
Q

The classical T cell mediated inflammatory reaction is called?

A

**Delayed-type hypersensitivity

TB test is type of delayed reaction

29
Q

Types Of type IV disease

A
MS, rheumatoid, 
type 1 diabetes, 
Crohns, 
contact dermatitis (poison ivy)
Chronic Infections (tb)
30
Q

Types of type I syndromes

A

Food alergy, asthma, allergic rhinitis

31
Q

SLE systemic lupus erythematosus is what type of hypersensitivity?

A

Type III

32
Q

Type 1:

Pathologic immune mechanism

A

TH2 cells, IgE antibodies, mast cells, eosinophils

33
Q

Type 1:

Mechanism of tissue injury and disease

A

Mass cell derived mediators (vasoactive amines, lipid mediators, cytokines)

Cytokine-mediated inflammation (eosinophils, neutrophils)

34
Q

Immediate type 1 hypersensitivity is a type of pathologic reaction that is caused by what?

A

Release of mediators from mast cells

35
Q

Type 1 hypersensitivity is most often triggered by what?

A

Production of IgE Ab against environmental Ags and the binding of IgE to Mast cells

36
Q

IgE-Fc∑R1 binding has high affinity for ?

A

IgE

37
Q

What are the sequence of events in the development of immediate hypersensitivity?

A
  1. production of IgE after activation of Th2 cells by 1˚ exposure to allergen
  2. Binding of IgE to Fc receptors of mast cells
  3. Release of mediators by mast cells after 2˚ exposure to Ag and cross-linking of the membrane-bound IgE by Ags
38
Q

The activation of TH2 cells causes what to happen to start production of IgE

A

Stimulation of IgE class switching in B cells

39
Q

What mediators case Imediate HS reaction within minutes

A

Mast cells releasing Vasoactive amines, lipid mediators

40
Q

What mediator cause late-phase reaction within 6-24 hrs.after repeat exposure?

A

Mast cells releasing Cytokines

41
Q

Examples of type 1 hypersensitivity

A
Anaphylaxis
Acute urticaria
Allergic rhinitis
Asthma
Food allergy
42
Q

Type 2 hypersensitivity:

Pathological immune mechanism

A

IgM, IgG, antibodies against cell surface of extracellular matrix antigens

43
Q

Type 2 hypersensitivity

mechanism of tissue injury and disease

A

Complement and Fc receptor mediated recruitment and activation of leukocytes (Neutrophils, macrophages)

Opsonization and phagocytosis of cells

Abnormalities in cellular function, e.g. hormone receptor signaling

44
Q

Examples of type 2 hypersensitivity

A
Hemolytic anemia
Thrombocytopenic purpura
Goodpasture syndrome
Graves disease
Myasthenia gravis
Pemphigus vulgaris
Blood Transfusion rxn
Rheumatic fever
45
Q

Type 3 hypersensitivity:

Pathological mechanism:

A

Immune complexes of circulating antigens and IgM or IgG antibodies deposited in vascular basement membrane of blood vessel

46
Q

Type 3 hypersensitivity mechanism of tissue injury or disease

A

Complement and Fc receptor mediated recruitment and activation of leukocytes

47
Q

Type 3 is mediated by the deposition of what in BV

A

Soluble Ab-Ag complexes formed in circulation

48
Q

The complexes initiate the complement to release what anaphylatoxin products

A

C3a and C5a

49
Q

Examples of type 3 hypersensitivity

A
Systemic lupus
polyarteritis nodosa
post-strep glomerulonephritis
serum sickness
arthus reaction
50
Q

Type 4 hypersensitivity

pathological mechanism

A
CD4 Tcells (cytokine-mediated inflammation)
CD8 CTLs (T-cell mediated cytolysis)
51
Q

Type 4 hypersensitivity

mechanism of tissue injury or disease

A
  1. Macrophage activation, cytokine-mediated inflammation

2. Direct target cell lysis, cytokine-mediated inflammation

52
Q

The major causes of T-cell mediated (type 4) hypersensitivity is?

A

Autoimmunity and exaggerated or persistent response to environmental Ag

53
Q

**Type 4 tissue injury may also accompany a T-cell response to microbes such as

A

M. tuberculosis

54
Q

Type 4 killing of host cells is caused by?

A

CD8 CTLs

55
Q

Type 4 cytokine mediated inflammation and tissue injury is primarily caused by

A

Cytokines produced by CD4 Th1 and Th17 cells

56
Q

What are Th1 cells

A

Th1 cells protect against intracellular organisms and secrete IFN¥ and TFNå. They help activate B-cells stimulation to secrete IgG, macrophages, and assist in activation of CD8. **ˆIFN-¥ inhibits IgE production reducing allergic responses

57
Q

What are Th2 cells

A

Protect against Extracellular organisms and secrete IL-4,5,10, and 13. release mediators that cause sneezing, coughing, and diarrhea to expel extracellular microbes

58
Q

HS type systemic lupus erythematous

A

Type 3

59
Q

HS type rheumatoid arthritis

A

Type 2 and 4

diagnostic test for rheumatoid factor

60
Q

HS type MS

A

Type 4

61
Q

HS type Diabetes mellitus type 1

A

TYPE 4

62
Q

HS type Inflammatory bowel

A

Type 4