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immunology > lect 16 > Flashcards

lect 16 Flashcards

1
Q

where is AIRE expressed

A

in lymphoid organs

thymic epithelial cells- positive selection

dendritic cells- negative selection

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2
Q

what results from the absense of AIRE in humans

A

autoimmune polyendocrine syndrome

APS-1

bc central tollerance missing

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3
Q

what are antigens that we have a tolerance to called

A

tolerogen or tolerogenic antigen

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4
Q

what are the mechanisms of central B cell tolerance

A

deletion- apoptosis
receptor editing
anergy
ignorance

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5
Q

B cell central tolerance +++ strength

A

apoptosis

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6
Q

B cell central tolerance + strength

A

anergic cell

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7
Q

B cell central tolerance +/- strength

A

mature B cell that is clonally ignorant

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8
Q

B cell central tolerance - strength

A

mature B cell

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9
Q

what happnes to the escapees of central tolerance

A

anergy due to no costimulatory singnal

deletion- FAS/FASL interactions - activates induced cell death

involves regulatory and supressor T cells

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10
Q

self rective B cells generated

A

druing immune reaction bc of SHM in gernal centre (affinity maturation)

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11
Q

what is the molecular basis of B cell anergy

A

B cells get only signal 1 from the antigen leading to anergy

follicular exclusion

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12
Q

what is follicular exclusion

A

cells excluded
from B-cell follicles in spleen &
LN; don’t receive survival signals
(die by neglect)

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13
Q

molecular basis of T cell anergy

A

only get one signla from Ag leading to anergy and no expression of IL2

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14
Q

Deletion of auto-reactive active T lymphocytes in the
periphery is due to

A

activation of the FAS receptor

ACID
activation induced cell death

anergic B cells also express Fas and can be eliminated this way

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15
Q

what disease results from mutated Fas

A

ALPS

autoimmune lymphoproliferative syndrome

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16
Q

mice with Fas and FasL mutations

A

lps and gld mice

autoimmune disease with increase numbers of lymphocytes

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17
Q

what initiates oral tolerance

A

encounter of food antigens with GALT- Ags enter circulation and presented by APC to T cell in absence of costiumulation by APC or B7

leads to T cell anergy

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18
Q

what plays an important role in oral toelrance

A

gut microbiome

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19
Q

what is the etiology of autoimmune diseases

A

genetic factors
environmental
interaction of genetic and environmental factors
drug and hormonal triggers

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20
Q

what are the genetic factors of autoimmunity

A

family clustering
- polygenic
-MHC(HLA) associated
-non HLA genes

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21
Q

what are the enviromental factors of autoimmunity

A

microbial and truama

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22
Q

what is associated genetically with autoimmune diseases

A

HLA types and Sex

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23
Q

environmental susceptibility types

A

sequestered Ags
molecular mimicry
polyclonal activation
innaproperiate expression class II MHC

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24
Q

what are the immunoprivelaged sites

A

eyes
testes
ovaries
placenta

dont develop a classical immune response

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25
Q

what sites are autoantigens protected

A

cartilage
neuronal antigens

26
Q

what causes antigens to be released from immunoprivelaged sites

A

physical disruption OR infection

27
Q

explain molecular mimmickry

A

a normally self reactive B cell wont activate from self antigen bc it wont have T cell help

if a B cell is reacting to microbial antigen that looks like our own, itll have T cell help and then produce antibodies that will react to our own antigens

28
Q

explain polyclonal activation

A

Lypopolysaccharide (PAMPs) from a gran -ve bacteria interacts with activating receptors on B cells

this will lead to intracellular detection of pathogenic patterns of DNA

29
Q

diabetes mellitis patients versus normal

A

Type 1 diabetes

B cells express class II and I MHC but they are only supposed to express class I

leads to activation of autoreactive CD4+ T cells

30
Q

explain innaproperiate expression of class II MHC

A

Expression of class II MHC on cells
that do not normally express class II
MHC can activate autoreactive
CD4+ T cells

31
Q

what causes the transfer of autoimmunity

A

tranfering CD4+ T cells

and a lack of T reg cells

32
Q

what increases autoimmunity

A

specific HLA alleles

33
Q

what is necessary to have an autoimmune reaction

A

interaction bw TCR and self peptide AND

MHC and self peptide

34
Q

how do T regs supress autoreactive t h cells

A

they supress CD4+ t cells that interact with the same ppetide or different peptide if they are all intercating with the same APC

lleads to linked supression

35
Q

what is an example of an immunosupressant

A

cyclosporin A

36
Q

what can be used as treatment for autoimmune diseases

A

immunosupressive therapy:
immunosupressants
general anti inflamamtory drugs
depletion of CD4+ t cells using anti CD4 antibody

other treatment:
targetted therapies
oral tolerance
block only antigen activated T cells

37
Q

does depletion of CD4 T cells using anti-CD4 antibody work

A
  • Worked in mice
  • Not successful in humans; timing of treatment?
    *Humans diagnosed in later stages of disease compared to mouse models
38
Q

what are some general targeted therapies for autoimmune treatment

A

anti cytokine antibodies or blockers

Rituximab

39
Q

what is rituximab

A

mAb against B cell CD20 - promotes B cell apoptosis and ADCC

helpful for RA?

40
Q

what are some anti cytokine antibodies and what do they do

A

block TNF-a

embrel
remicade
humira

41
Q

what are anti cytokine antibodies used for

A

crohns disease
ankylosing spondyylitis

42
Q

what is the advantage of blocking only ag activated T cells

A

overall immunity is not lowered

43
Q

what is the challenge of blocking only ag activated T cells

A

target only activated T cells

  1. we can use mAb against IL2-R, a subunit

has promising resulst but BAD for T reg

  1. block specific asssociated TCR chains
44
Q

what type of autoiimune is SLE

A

type 3

formation of immune complexes that lead to compliment activation and deposition in kidneys- inflammation

45
Q

how is SLE distributed in sex

A

10:1 females to males

can be exacerbated during pregnancy

there is a genetic predisposition and an HLA association

46
Q

what is the symptom and underlying cause of SLE

A

unknown ag

butterfly like rash and high levels of anti DNA abs

47
Q

what is the visual symptom of hashimotos thyroiditis

A

goiter formation and hypothyroidism

48
Q

what is the cuase of hashimotos thyroiditis

A
  • Autoantibodies against microsomal &
    thyroglobulin
  • Sensitized T H1 cells for thyroid antigen
  • Intense infiltration of the thyroid gland
    by mononuclear cells
  • Interfere with iodine uptake & leads to
    decreased production of thyroid
    hormones
49
Q

what mediates MS

A

T cells

infiltrate the brain and cause inflammatory lesions

inflammatory lesions destroy myelin shief of CNS

autoreactive TH1 cells activate macrophages
-leads to inflammation
-inc macrophage, neutrophil, mast cells
-Fas mediated death of oligodendeocytes

50
Q

what causes MS

A

not known

sequestered release of myelin Ags

mollecular mimicry following viral infection (EBV)

51
Q

what is the gentic component of MS

A

HLA class II

DR15, DQ6

52
Q

what cells are in type 1 IDDM

A

CD8+

TH1

Cytokines

53
Q

what is the genetic component of type I diabetes

A

HLA Class II genes

HLA DQ2. DQ8 and non HLA genes

54
Q

what occurs in Type I diabetes

A

destrction of insulin producing B islet cells of pancreas leads to autonatibodies formation

55
Q

what cells are involved in rheumatoid artheritis

A

autoreactive CD4+ TH1 cells

CD4+ TH17 and cytokines lead to bone destruction

macrophages and fibroblasts cause a feed forward inflammation

56
Q

what cytokines in RA

A

IFNY and IL17

57
Q

genetic component of RA

A

some HLA DR4 alleles

58
Q

what are the immune complexes in RA

A

rheumatoid factor ++

IgM antibody against Fc region of igG molecules

59
Q

what is RA

A

chronic inflammation and ersion of synoviun and bone

60
Q
A

immunology (30 decks)

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