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Pathology > Lec7-8 Immunopathology/Amyloids > Flashcards

Lec7-8 Immunopathology/Amyloids Flashcards

1
Q

4 main types of hypersensitivity reactions and examples

A
  1. Immediate [allergic], IgE mediated degranulation of mast cell
    Ex. Asthma
  2. Antibody dependent, IgG autoantibodies
    Ex. Goodpasture syndrome
  3. Immune complex, IgG/C3/Antigen mediated
    Ex. Postinfectous GN, SLE, Vasculitis
  4. Cell mediates, T cell mediated
    Ex. Type I DM, Sarcoid
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2
Q

Two mech of immunologically-mediated disease

A
  • hypersensitivity disease: react to foreign antigens via hyperreactive inflammatory response
  • autoimmune disease: react to self antigens via normal inflammatory response
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3
Q

Bronchial asthma - what is it? What pathology?

A
  • Type I hypersensitivity reaction
  • Hypertrophy of bronchus smooth muscle
  • Edema
  • Leukocyte infiltration [eosinophils!]
  • glandular hyperplasia and increased mucus secretion into bronchus lumen
  • epithelial damage and sloughing
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4
Q

3 Subtypes of Type II Hypersentivitiy Rxns

A

Opsonization and phagocytosis
- may not have inflammation

Complement and Fc mediated inflammation
- neutrophil activation, inflammation, tissue injury

Abnormal physiological response

  • no inflammation
  • ex. receptors, myasthenia gravis [blocks acetylcholine receptors]
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5
Q

Goodpasture syndrome

A

Type II Hypersensitivity
- react to collagen IV in basement membrane
- complement and Fc receptor mediated
inflammation causes neutrophil activation
- glomeruler necrosis and acute inflammation
- leads to renal dysfunction

clinical: dark brown urine, high serum creatinine, coughing up blood, hematuria, hypertension, decreased glomerular filtration

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6
Q

Post-Streptococcal Glomerulonephritis

A

Type III hypersensitivity

  • renal dysfunction, edema of eyelids, high BP, brown urine
  • subepithelial immune complex deposits [granular deposits]
  • may resolve on its own
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7
Q

Systemic Lupus Erythematosus [SLE]

A

Type III hypersensitivity
Reaction to nuclear antigens
- involves skin, joints, kidney, serosal membranes
- cannot resolve on its own, requires immunosuppressive therapy

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8
Q

5 most frequent sites immune complex deposition

A

skin: sun-exposure injury
glomerulus: high hemodynamic pressures + filtration function
synovium: mech trauma, high hemodynamic pressures + filtration function
endocardium: mechanical trauma, particularly valves

blood vessels: vascular turbulence, high pressure, particularly microvasculature + branch points of large BV

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9
Q

Type I Diabetes Mellitus

A

Target = Beta islet cells

Type IV hypersensitivity

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10
Q

Sarcoidosis

A

Type IV hypersensitivity

Causes Granulomas

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11
Q

Amyloid

A

pathologic accumulation proteinaceous substance deposited in extracellular space

Consists of insoluble aggregates fibrillar proteins, cross B pleated sheet

Diagnosis requires histologic identification

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12
Q

Amyloidosis

A

Group of diseases in which amyloids deposited

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13
Q

Amyloid properties

A
  • result of protein misfolding
  • self association of cross-B-pleated sheets form protofilament cores
  • assembly of protofilaments create amyloid fibrils
  • continuous non-branching fibers
  • each fiber 4-6 fibrils in parallel array
  • physical structure independent of clinical setting or chemical composition
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14
Q

Amyloid in histology

A
  • composed of mostly protein fibrils
  • stains blue-black with acidified iodine
  • resembles cellulose or starch
  • progressive extracellular accumulation
  • pressure atrophy, functional disruption
  • organs deformed, firm, enlarged
  • amorphous, hyaline substance [H&E]
  • pink-orange-red [congo red stain]
  • red-green birefringence [polarized light]
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15
Q

What does congo red show?

A

amyloids show up eosinophilic in normal light

show up neony green in polarized light

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16
Q

AL amyloid

A
  • misfolded form of immunoglobulin light chain
  • deposits in plasma cells
  • stimulus = unknown, possibly carcinogen
  • get monoclonal B proliferation –> plasma cells –> lots of Ig light chains
  • excess protein and limited proteolysis leads to aggregation
  • primary systemic amyloidosis
  • ex. multiple myeloma
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17
Q

AA amyloid

A
  • from serum amyloid-associated protein [SAA]
  • deposits in liver [acute phase response]
  • stimulus = chronic inflammation
  • get macrophage activation –> IL-1/6 –> liver cells
  • excess SAA protein and limited proteolysis lead to aggregation
  • secondary system amyloidosis
    ex. chronic inflammatory conditions
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18
Q

B-amyloid [AB] - what disease type?

A
  • from amyloid precursor protein [APP]
  • cerebral deposits [plaques]
    senile cerebral localized amyloidosis
    ex. alzheimer disease
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19
Q

ATTR amyloid

A
  • from Transthyretin [TTR]
  • mutation [genetic syndrome, aging]
  • mutant/abnormal protein aggregates
  • senile/hereditary amyloidosis
    ex. senile systemic/cardiac amyloidosis
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20
Q

Chemical Composition of Amyloid

A

95% major amyloid fibril protein
- AL, AA, AB, etc

5% minor components

  • serum amyloid P component
  • proteoglycans, glycosaminoglycans
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21
Q

Pathogeneisis of Amyloidosis

A
  1. Abnormal folding of protein, becomes unstable
  2. Self-associates into oligomers/fibrils, becomes insoluble
  3. Deposits in extracellular tissue, causes pressure atrophy
  4. Disrupts normal tissue function
22
Q

Why do misfolded proteins turn into amyloids instead of being degraded in some people?

A

High level normal proteins [misfold when accumulate]

  • increased production from aging
  • decreased excretion
  • decreased proteolysis

Mutation causes misfolding of abnormal proteins
- hereditary [ATTR] or acquire [prion]

23
Q

Classification of Amyloidosis

A

Tissue distribution: either localized or systemic

If systemic:

    • primary: due to plasma cell proliferation, clinically unrecognized
    • secondary: due to chronic inflammatory disorder

Also can be hereditary/familial

24
Q

Prognosis of generalize system amyloidosis

A
  • progressive, unremitting
  • median survival 2-5 yrs [primary < secondary]
  • cardiac or renal complications
25
Q

Prognosis localized or familial amyloidosis

A

15-20 years

longer than generalized

26
Q

treatment for amyloidosis

A
  • reduce precursor protein synthesis
  • inhibit fibrillogenesis
  • amyloid can rarely be resorbed
27
Q

Origins of autopsy

A
  • 18th century
  • Giovanni Battista Morgagni
  • first great autopsy pathologist
  • publicly opposed galileo’s theories
28
Q

19th century autopsy

A

Marie-Francois Xavier Bichat = father of histology

Rudolph Virchow: said cellular derangement is at basis of disease

29
Q

Does histamine lead to transudate or exudate? Why?

A
  • Histamine is a vasodilator and increases vascular permeability
  • Causes cells and fluid to leave = exudate
30
Q

Type III hypersenstivity mechanism and pathology?

A
  • circulating immune complex is deposited in kidney
  • activated inflammatory pathway in kidney
  • causes vasculitis [fibrinoid necrosis]
31
Q

Type IV hypersensitivity examples, mech, pathology?

A

examples: type I diabetes, sarcoidosis, contact dermatitis, transplant rejection
mech: CD4 or CD8 T cell activation
pathology: granulomas

32
Q

Type II hypersensitivity examples, mech, pathology?

A

examples: goodpastures, autoimmune hemolytic anemia, graves

immune mech: antigen on cell surface or tissue surface

pathology: complement activation or acute inflammation

33
Q

Definition of polyp

A

growth protruding above epithelial surface

34
Q

Clinical signs of bronchial astham

A
  • wheezing, breathlessness, tight chest, cough
35
Q

clinica sign of systemic analphylaxi

A
  • itching, hives, difficult breathing, diarrhea, shock
36
Q

What is myasthenia gravis

A
  • type II hypersensitivity

- blocks acetylcholine receptor

37
Q

what is grave’s disease

A
  • stimulates TSH receptor

- type II hypersensitivity

38
Q

what type of hypersensitivity is autoimmune hemolytic anemia?

A
  • type II

- attacks red cell antigen

39
Q

What type of hypersensitivity is post-strep glomerulonephritis?

A

type III

40
Q

What type of hypersensitivity shows granular immunofluorescence and which linear?

A

Type III is granular

Type II is linear [goodpasture]

41
Q

What is multiple myeloma? What amyloidosis associated?

A
  • cancer of plasma cells where overproduce one type of abnormal antibody
  • overproduction of antibody can lead to AL amyloidosis
42
Q

What disease associated with AL amyloid?

A

multiple myeloma

43
Q

What disease associated with AA amyloid?

A

chronic inflammatory conditions [rheumatoid arthritis

44
Q

If you see subepithelial deposits in glomerulus what should be first thought?

A

post stre glomerulonephritis

45
Q

What is heparin?

A

An anticoagulant

46
Q

What are schistocytes?

A

Fragmented RBC

a sign of disseminated intravascular coagulation

47
Q

Most likely cause arterial thrombus?

A

Endothelial injury

48
Q

What inflammatory cell involved primarily in bronchial asthma?

A

eosinophils

49
Q

What form of amyloid associated with alzheimers? What precursor?

A

AB amyloid, from APP

50
Q

What type of necrosis is associated with type III hypersensitivity

A

fibrinoid necrosis

51
Q

How do you tell if a granuloma in lung is sarcoid or TB?

A
  • granulomas of sarcoid have no central necrosis, those of TB do
  • sarcoid granulomas often surrounded by fibrosis [scar tissue]
52
Q

What are 4 diseases that cause granulomas and where?

A

in lung: sarcoidosis, TB
in intestine: crohns
in skin: leprosy

Pathology (15 decks)

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