MedEd Immuno 1 Flashcards

1
Q

cells of innate immunity (6)

A

neutrophils
basophils
eosinophils
macrophages
natural killer cells
dendritic cells

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2
Q

cells of adaptive immunity (2)

A

B and T cells

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3
Q

which type of immunity is fast vs slow

A

innate = fast
adaptive = slow

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4
Q

soluble components of the innate immune system

A

complement
acute phase proteins
cytokines / chemokines

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5
Q

describe activation of the innate immune system

A

produce phagocytes and release them into blood
endothelial cells express adhesion molecules - allows cells to stick and migrate
phagocytosis
oxidative / non oxidative killing
macrophages communicate to t cells
neutrophils die and form pus

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6
Q

which immune cells is pus mainly composed of

A

neutrophils

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7
Q

what is the point of dendritic cells in terms of the 2 types of immunity

A

mediate the transition from innate to adaptive immunity

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8
Q

what type of cell is a dendritic cell

A

phagocyte

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9
Q

what do dendritic cells do after phagocytosis (3)

A

upregulate expression of HLA
express costimulatory molecules
migrate via lymphatics to lymph nodes

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10
Q

what receptor do dendritic cells use to migrate to lymph nodes

A

CCR7 receptor

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11
Q

what do B and T cells do in primary vs secondary lymphoid organs

A

primary - developed and mature
secondary - interaction with pathogens

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12
Q

which organs are primary vs secondary lymphoid organs

A

primary - bone marrow and thymus
secondary - spleen, lymph nodes, MALT

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13
Q

what is humoral vs cellular immunity

A

humoral = deals with antigens from freely circulating pathogens (outside cell)
cellular = deals with clearing the infected cell

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14
Q

lifecycle of a T cell

A

pre T cells made in thymus
selection in thymus
CD4 or CD8 T cells made

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15
Q

lifecycle of B cell

A

produced in BM: pro B cell –> pre B cell
develop into IgM secreting B cells
then develop into plasma cells or undergo class switching to make IgG / IgE / IgA

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16
Q

how does T cell selection work in the thymus

A

low affinity for HLA –> not selected (inadequate reactivity)
intermediate affinity for HLA –> selected
high afifnity for HLA –> not selected (autoreactivity)

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17
Q

what % of produced T cells are selected in the thymus

A

10%

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18
Q

which T cells go on to make CD4 t cells and which go on to make Cd8 T cells

A

cd4 = affinity for HLA II
cd8 = affinity for HLA I

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19
Q

what are cd4 T cells aka

A

T helper cells

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20
Q

what are cd8 T cells aka

A

T killer cells

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21
Q

3 functions of cd 4 / t helper cells

A

recognise extracellular protein peptides presented on HLA2
help development of full B cell response
help development of some cd8 t cell response

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22
Q

3 functions of cd8 / t killer cells

A

reconise intraceullar protein peptides presented on HLA1
kill cells

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23
Q

2 ways cd8 / t killer cells can kill

A

via perforin / granzyme
via Fas ligand expression

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24
Q

describe B cell selection in the BM

A

no recognition of self = survive
recognition of self = not selected

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25
Q

what are the 2 fates of a B cell selected in the BM

A

become IgM secreting plasma cell
undergo class switching to become IgG/A/E B cell

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26
Q

which pathway of the B Cell (IgM or class switching) requires T cells and which is T cell independent

A

IgM = T cell independent
class switching = T cell dependent

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27
Q

what reaction do B cells undergo to become IgG/A/E B cells

A

germinal centre reaction

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28
Q

describe the germinal centre reaction

A

dendritic ells prime CD4+ T cells
CD4+ T cells help B cell differentiation
B cell proliferation with somatic hypermutation isotype switching

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29
Q

what do CD4+ T cells require to help B cell differentiation

A

CD40L:CD40

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30
Q

2 roles of ABs

A

identification of pathogens and toxins
interaction with and activation of other immune componnets to remove pathogens

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31
Q

which part of the AB is needed to identify pathogens

A

Fab

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32
Q

which part of the AB is needed to activate other immune components and remove the pathogen

A

Fc

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33
Q

which cell exists in immature form in periphery where they recognize pathogens, then mature and become adapted for presenting antigens to T cells in lymph nodes?

A

dendritic cells

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34
Q

what is the complement cascade

A

sequence of reactions that enhances the rest of the immune system

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35
Q

what is the starting point of the complement cascade

A

inactive circulating proteins

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36
Q

what is the activation stage of the complement cascade

A

proteases cleave the protein and initiate the cascade

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37
Q

what is the end point of the complement cascade

A

membrane attack complex (MAC) - attacks the pathogen cell membrane

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38
Q

fragments released during the complement cascade have 4 other effects, what are they?

A

increase vascular permeability
opsonise immune complexes and pathogens
activate phagocytes
promote mast cell and basophil degranulation

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39
Q

name the pathways of the complement cascade

A

classical or alternative or MBL
–> C3
–> final common pathway
–> MAC

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40
Q

what are the components of the classical pathway

A

C1 / C2 / C4

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41
Q

what are the components of the MBL pathway

A

C4 / C2

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42
Q

what are the components of the final common pathway

A

C5 / C9

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43
Q

how does the classical pathway kill pathogens

A

Ag-AB complexes

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44
Q

how does the alternative pathway kill pathogens

A

bacterial cell wall attack

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45
Q

how does the MBL pathway kill pathogens

A

attacks microbial cell surface and carbs

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46
Q

name 3 broad classes of immunodeficiencies

A

primary
secondary
physiological

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47
Q

3 classes of primary immune deficiencies

A

innate
adaptive
complement

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48
Q

4 classes of causes of secondary immune deficiencies and 2 examples of each

A

infections - HIV, measles
biochemical disorders - malnutrition, renal impairment
malignancy - leuakaemia, lymphoma
drugs - steroids, cytotoxics

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49
Q

3 physiological states of immune deficiency

A

neonates
pregnancy
old age

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50
Q

name 3 PIDs of failure to produce neutrophils

A

reticular dysgenesis
kostmann syndrome
cyclical neutropaenia

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51
Q

inheritance pattern of reticular dysgenesis

A

AR

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52
Q

inheritance pattern of kostmann

A

AR

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53
Q

inheritance pattern of cyclical neutropaenia

A

AD

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54
Q

mutation in kostmann

A

HAX1 protein

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55
Q

mutation in cyclical neutropaenia

A

ELA-2

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56
Q

PC of cyclical neutropaenia

A

episodic neutropaenia every 4-6 weeks

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57
Q

Tx for PIDs of failure to produce neutrophils

A

G-CSF

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58
Q

PID of defect of phagocyte migration

A

leukocyte adhesion deficiency

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59
Q

3 PC of leukocyte adhesion deficiency

A

high neutrophil count
absent pus formation
delayed umbilical cord sloughing

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60
Q

pathogenesis of leucocyte adhesion deficiency

A

deficient in CD11a/18 (expressed on neutrophils, binds to ICAM-1 on endothelial cells)
deficiency = neutrophils can’t exit bloodstream

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61
Q

Tx of leukocyte adhesion deficiency

A

haematopoietic stem cell transplant

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62
Q

PID of defect of oxidative killing

A

chronic granulomatous disease

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63
Q

pathogenesis of chronic granulomatous disease

A

deficiency of NADPH oxidase complex –> impaired killing

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64
Q

4 clinical signs of chronic granulomatous disease

A

granulomas
lymphadenopathy
hepatosplenomegaly
pus

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65
Q

what organisms are chronic granulomatous disease pts susceptible to

A

catalase positive organisms eg pseudomonas, listeria, aspergillus, candida, e coli, s.aureus, serratia

66
Q

test for chronic granulomatous disease

A

nitroblue tetrazolium test
dihydrorhodamine flow cytometry test

67
Q

result of nitroblue tetrazolium test in CGD

A

NO colour change from yellow to blue

68
Q

result of dihydrorhodamine flow cytometry test in CGD

A

DHR oxidised to fluroescent rhodamine

69
Q

Tx of CGD

A

IFNy

70
Q

what cytokine deficiencies can cause issues

A

IL12 or IFNy
(both the cytokine or the receptor)

71
Q

what are IL12 / IFNy deficient pts susceptible to

A

intracellular organisms eg mycobacteria or salmonella

72
Q

child presents with recurrent bacterial and fungal infections. the nitroblue tetrazolium test is performed where the mixture remains yellow. Dx?

A

chronic granulomatous disease

73
Q

3 PIDs with failure to produce lymphoid progenitors

A

reticular dysgenesis
X linked SCID
ADA deficiency

74
Q

when do pts with failure to produce lymphoid progenitors present and why

A

after first 3 months of life, as maternal IgG protection wears off

75
Q

pathogenesis of reticular dysgenesis

A

mutation of adenylate kinase 2 (AK2)

76
Q

pathogenesis of X linked SCID

A

mutation of y-chain on IL2R
- poor cytokine response

77
Q

what cells are absent in reticular dysgenesis

A

lymphocytes / neutrophils / macrophages / platelets

78
Q

which cells are absent / weird in X linked SCID

A

no T cells or NK cells
B cells are IMMATURE

79
Q

pathogenesis of ADA deficiency

A

adenosine deaminase deficiency
- needed for lymphocyte metabolism

80
Q

which cells are present in low quantities in ADA deficiency

A

B, T, NK cells

81
Q

Tx for failure to produce lymphoid progenitors PIDs

A

haematopoeitic stem cell transplant

82
Q

Tx for ADA deficiency

A

Peg - ADA

83
Q

which PID has a failure of T cell maturation

A

Di George syndrome

84
Q

pathogenesis of Di george syndrome

A

deletion of 22q11.2

85
Q

Sx / signs of Di George syndrome

A

CATCH22
cardiac abnormalities
abnormal facies
thymis aplasia
cleft palate
hypocalcaemia
22q11.2 deletion

86
Q

cellular level abnormalities in di george syndrome

A

reduced T cells
normal B cells but reduced IgG

87
Q

how does di george syndrome progress

A

gets better with age

88
Q

Tx of di george syndrome

A

thymic transplant

89
Q

what PID has failure of Cd4/8 selection

A

bare lymphocyte syndromes

90
Q

how are bare lymphocyte syndromes type 1 and 2 different

A

1 = defect in gene expression of MHC1 –> deficiency of cd8
2 = defect in gene expression of MHC2 –> deficiency of cd4

91
Q

what Igs are low in bare lymphocyte syndrome type 2

A

IgG,A,E (no cd4 help with class switching)

92
Q

what PID has a failure of B cell development

A

bruton’s x linked alpha gammaglobulinaemia

93
Q

pathogenesis of bruton’s x linked alpha gammaglobulinaemia

A

defective b cell tyrosine kinase gene
–> pre B cells can’t develop into mature B cells
–> no circulating IgG after 3 months of life

94
Q

clinical sign of bruton’s x linked alpha gammaglobulinaemia

A

absent lymph nodes and tonsils

95
Q

Tx of bruton’s x linked alpha gammaglobulinaemia

A

IV Ig

96
Q

PID of failure to produce immunoglobulins

A

selective IgA deficiency
combined variable immune deficiency

97
Q

prevelance of selective IgA deficiency

A

1/600

98
Q

PC of selective IgA deficiency with %s

A

66% asymptomatic
33% recurrent respiratory tract infections

99
Q

what Igs are low in CVID

A

A,G,E

100
Q

PC of CVID

A

recurrent resp / GI infections
- AID
- granulomatous disease

101
Q

what PID has failure of class switching

A

hyper IgM syndrome

102
Q

pathogenesis of hyper IgM syndrome

A

T cell defect
- mutation in CD40L expressed by T cells
- encoded on Xq26
–> no class switching

103
Q

Ig levels in hyper IgM syndrome

A

high IgM
no Ig A / G / E

104
Q

Ix for adaptive immunodeficiencies

A

WBC
lymphocyte subsets inc cd4 / cd8
serum Ig / protein electrophoresis

105
Q

child with recurrent infections who had seizures as a baby. Dx?

A

di george syndrome

106
Q

what is the main clinical consequence of complement deficiency

A

increased susceptibility to encapsulated organisms eg s.pneumoniae, h.influenzae, n.meningitidis

107
Q

which failure of the classical pathway is most common

A

c2

108
Q

PC of classical pathway deficiency

A

recurrent infections
severe skin disease

109
Q

all patients with C2 deficiency will have which AID?

A

SLE

110
Q

when does failure of MBL pathway present and why

A

only if other precipitant eg prem / chemo / HIV / AB def
30% heterozygous for MBL def / 6-10% no circulating MBL

111
Q

how does failure of alternative pathway present

A

encapsulated bacterial infections

112
Q

how does failure of final common pathway present

A

encapsulated bacterial infections

113
Q

which factors are deficient in final common pathway failure

A

c3 and c5-9

114
Q

name 2 secondary complement deficiencies

A

SLE
nephritic factors

115
Q

why does SLE cause a secondary complement deficiency

A

consumption of c3 and c4

116
Q

why does nephritic factors cause secondary complement deficiency

A

auto ABs against complement

117
Q

what 2 clinical features are nephritic factors associated with

A

glomerulonephritis
partial lipodystrophy

118
Q

Ix for complement deficiencies

A

complement levels - c3/4 or c1 etc
CH50 - classical pathway activity
AP50 - alternative pathway activity

119
Q

what condition has low c1 esterase inhibitor

A

hereditary angioedema

120
Q

which condition has low c3 and c4

A

active lupus

121
Q

Mx of primary complement deficiencies

A

screen family members
prophylactic vaccination / ABx
aggressive Tx of infections

122
Q

severe childhood onset SLE with normal c3 and c4

A

c1q deficiency

123
Q

mebranoproliferative nephritis with abnormal fat distribution

A

c3 deficiency with nephritic factor

124
Q

meningococcal meningitis with FHx of sibling dying young

A

C7 deficiency

125
Q

recurrent infections when neutropaenic following chemo, but previously well

A

MBL deficiency

126
Q

is it auto inflamm or auto immune that has HLA associations

A

autoimmune

127
Q

is it auto inflamm or auto immune that has auto ABs

A

autoimmune

128
Q

name a rare monogenic autoinflamm condition

A

FMF - familial mediterranean fever

129
Q

PC of FMF

A

periodic fevers and serositis

130
Q

pathogenesis of FMF

A

abnormal TNFa / IL1 signalling due to MEFV mutatoin

131
Q

what complex is involved in FMF

A

pyrin-marenostrin complex (controls activation of neutrophils)

132
Q

Tx of FMF

A

colchicine
anakinra - IL1R antagonist
etanercept - TNFa inhibitor

133
Q

name polygenic autoinflamm disorders

A

Crohns
UC
osteoarthritis
GCA
Takayasau’s arthritis

134
Q

name some mixed pattern autoinflamm/autoimmune diseases

A

ankylosing spondylitis
psoriatic arthritis
Behcet’s

135
Q

what HLA mutation does mixed pattern disease often have

A

HLA B27 mutation

136
Q

what cells does the HLA B27 mutation affect

A

Cd8 and Th17 cells (adaptive)
NK cells (innate)

137
Q

name some polygenic autoimmune conditions

A

RA
myasthenia gravis
pernicious anaemia
SLE

138
Q

what mutations are present in polygenic autoimmune conditions

A

PTPN22 -‘ve T cell regulator
CTLA4 -‘ve T cell regulator

139
Q

what is the HLA susceptibility allele of goodpastures

A

HLA DR15

140
Q

what is the HLA susceptibility allele of graves / SLE

A

HLA DR3

141
Q

what is the HLA susceptibility allele of T1DM

A

HLA DR3/4

142
Q

what is the HLA susceptibility allele of RA

A

HLA DR4

143
Q

name 3 monogenic autoimmune disorders

A

APECED
IPEX
ALPS

144
Q

what is APECED

A

central tolerance breakdown

145
Q

pathogenesis of APECED

A

mutation of TF AIRE - responsible for expression of self antigens in thymus to enable negative selection of autoreactive T cells

146
Q

5 features of APECED

A

Autoimmune
polyendocrinopathy
candidiasis
ectodermal
dystrophy

147
Q

what is IPEX

A

T reg abnormality

148
Q

pathogenesis of IPEX

A

mutation in FoxP3 required for T reg cell development

149
Q

Sx of IPEX

A

diarrhoea / diabetes / dermatitis

150
Q

what does IPEX stand for

A

immune dysregulation
polyendocrinopathy
enteropathy
x linked

151
Q

pathogenesis of ALPS

A

mutation in Fas pathway
T cells NOT killed in thymus –> dodgy T cells enter periphery

152
Q

what does ALPS stand for

A

autoimmune
lymphoproliferative
syndrome

153
Q

3 clinical features of ALPS

A

large spleen / lymph nodes
autoimmune cytopaenia
lymphoma

154
Q

what is type 1 hypersensitivity

A

immediate - Ag cross links IgE on mast cells –> degranulation

155
Q

what is type 2 hypersensitivity

A

AB dependent - ABs bind to surface Ag

156
Q

what is type 3 hypersensitivity

A

immune complex - Ag-AB complexes form in blood and deposit in tissues

157
Q

what is type 4 hypersensitivity

A

delayed - T cell mediated (Cd4 release cytokines, CD8 kill targeted cells)

158
Q

example of type 1 hypersensitivity

A

atopic eczema
anaphylaxis

159
Q

example of type 2 hypersensitivity

A

Graves
Myasthenia Gravis

160
Q

example of type 3 hypersensitivity

A

SLE
serum sickness

161
Q

example of type 4 hypersensitivity

A

T1DM
contact dermatitis