Hypersensitivities Type I-IV Flashcards

1
Q

hypersensitive

A

above and beyond normal response

-causes pathology

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2
Q

how many types of hypersensitivities?

A

4 types

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3
Q

type IV hypersensitivity

A

T cell mediated diseases

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4
Q

type I hypersensitivity

A

aka immediate hypersensitivity

-atopic diseases

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5
Q

atopic diseases

A

caused by Type I hypersensitivity

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6
Q

IgE

A

big player in type I hypersensitivity**

extra constant region domain
-allows it to bind Fc on mast cells

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7
Q

three properties controlling IgE?

A

1 half life of IgE
2 T cell control (need isotype switching)
3 cross-linking of IgE on surface of mast cells and basophils

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8
Q

half life of IgE?

A

2 days in serum (very short)

produced in response to allergens

half life increased when binds to mast cells and basos

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9
Q

receptor for IgE on mast cells and basos?

A

FcERI

high affinity

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10
Q

half-life of IgG

A

3 weeks woah!

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11
Q

receptors for IgE on B cells?

A

FcERII

low affinity

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12
Q

Th1 activation leads to?

A

IFN-gamma and IL-12
no upregulation of IgE

**suppressive the atopic reaction

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13
Q

Th2 activation leads to?

A
IL-4, IL-5 IL-13
leads to class switching (via IL-4) to IgE

**increases the atopic reaction

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14
Q

IL-5 activity?

A

stimulates maturation of eosinophils

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15
Q

allergen

A

antigen that gives rise to immediate hypersensitivity
-most are proteins

-usually taken in very small quantities that is sustained throughout life (ex/ dust)

food - large dose

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16
Q

mediators of IgE (intermediate) response in mast cells?

A

histamine, heparin, and tryptase (5 minutes)

also, newly generated (5-30 minutes)

  • arachidonic adic
  • leukotriene D4
  • prostaglandin D2

**vasoactive amines and lipid mediators

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17
Q

late phase reaction of mast cells immediate hypersensitivty?

A

2-10 hours later

-cyrokines, IL-4, TNF-alpha

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18
Q

released by eosinophils?

A

cationic granule proteins and eosinophil peroxidase

**to kill worms, but can kill self cells

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19
Q

what must occur for mast cell activation?

A

binding of IgE and must be CROSS-LINKED**

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20
Q

allergic rhinitis?

A

increased mucus secretion

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21
Q

wheal

A

extravasation of sera

22
Q

flare

A

axon reflex

23
Q

late phase reaction ?

A

4-6 hours after type I reaction
-can persist 1-2 days

infiltration of PMNs, eosinophils, macrophages, lymphocytes, basophils

occurs bc mast cells produce TNF-alpha and IL-1 which leads to increased extravasation

mast cells also produce neutrophil chemotactic factor

on-site release of IL-3, IL-5, IL-8, and GM-CSF

24
Q

normal function of IgE

A

protection against parasites

25
Type II Hypersensitivity
antibody mediated -IgG/IgM/FcR/C' initiating antigen is a surface antibodies bind FcR on tissue surface initiating effector cells binding of C1 to IgG or IgM activates C' cascade damages target cells -locallized to cells bearing antigens
26
"fixed antigens"
antibodies against cell surfaces are usually pathogenic antibodies against internal antigens are usually not pathogenic
27
C3a and C5a?
chemotaxis of PMNs, basophils, and eosinophils
28
normal phagocyte activation?
machophage binds Fc receptor and C3 receptor -results in phagocytosis and lysosomal fusion degrades cell
29
frustrated phagocytosis
cannot internalize complex instead, releases all of its enzymes to intravascular space and degrades tissue **occurs in hypersensitivity type II
30
hemolytic disease of the newborn (HDNB)
when mother Rh- and baby is Rh+ aka erythroblastosis fetalis during birth, mother will make IgM antibodies against Rh+ (there is some blood exchange during birth) -makes memory which will respond to next pregnancy if baby is Rh+
31
how to avoid erythroblastosis fetalis?
use Rhogam binds the Rh antigens and inhibits the mothers immune response from being exposed to it
32
antigens involved in HDNB?
``` Rhesus D most positive also Kell (K) antigen ```
33
using whole blood during transfusion?
giving someone serum (no good)
34
donated blood is what?
separated to serum and cells first
35
autoimmune hemolytic anemia
warm antibodies - different epitopes than transfusion rxn. (Rhesus) cold antibodies - high titer IgM -usually in old people during winter can be spontaneous or drug caused
36
myasthenia gravis
self-antibodies to AcH receptors extreme muscle weakness**
37
Type III Hypersensitivity
involve immune complexes soluble antigen** normally, taken care of by waste management -if not, lead to pathology can have interlacing collection with increased pathology
38
three groups of type III hypersensitivity
persistent infection autoimmune disease inhalation of antigen
39
normal waste management?
CR1 receptor on RBCs bind to immune complexes taken to spleen and liver where they are degraded
40
when immune complexes settle out?
in very small vessels -bring in baspohils, mast cells, macrophages results in leakiness (great area for immune complex) platelet aggregation occurs increase in BP, vascular turbulence, and complex deposition
41
arthus reaction
presensitized with IgG allergy shots so that it won't bind IgE get localized hemorrhage in 4-10 hours can lead to allergic alveolitis
42
serum sickness
induced by large injection of foreign antigen complexes deposit in blood vessels and tissues leads to arthritis and glomerulonephritis complication of equine serum therapy (horse) or antigen excess (acute infectious disease)
43
mechanisms of Type II and III
inflammatory pathways are identical -difference is initiator type II - fixed surface type III - soluble complement major mediator
44
delayed type hypersensitivity?
Type IV hypersensitivity T cells are mediator - effector T cells are stimulated - can lead to granulomas from macrophages
45
three types of DTH?
contact tuberculin (ex/ PPD test) granulomatous (clinically most important) -usually 28 days out
46
contact sensitivity stages?
sensitization and elicitation sensitization - 10-14 days in epidermis - ex/ poison oak/ivy (require haptens) - build memory cells elicitation - recruit CD4 T cells to site of contact pro-inflammatory cytokine driven -monocytes, macrophages -mainly CD4 T and small number of CD8
47
tuberculin type DTH?
looking for a recall - to see if you have been sensitized to it ex/ tuberculin skin test
48
granulomatous DTH?
usually persistance of macrophages - microbes that can resist killing - other cells cell can't destroy occurs with Th1 response
49
basis for classification of hypersensitivity?
Coombs and Gell
50
what immune complexes deposited the most?
small positively-charged ones
51
diseases assocaited with DTH?
tuberculosis, leprosy, schistosomiasis, sarcoidosis, Crohn's disease