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year 1 > principles immunology > Flashcards

principles immunology Flashcards

1
Q

what are 3 barriers to infection

A

skin
mucous
commensal bacteria

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2
Q

how does the skin protect against infection

A 
physical barrier 
tightly packed, highly keratinised 
undergo constant renewal and replacement
low pH and low oxygen
sebaceous glands - secrete hydrophobic oils, lysozyme, defensins, ammonia
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3
Q

how does mucous protect against infection

A

traps invading organisms
contains secretory IgA, enzymes such as lysozyme, defensins, antimicrobial peptides which directly kill pathogens, lactoferrin which starves bacteria of iron
cilia remove mucous

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4
Q

how does commensal bacteria protect against infection

A

compete with pathogens for scarce resources

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5
Q

what can the use of broad spectrum antibiotics cause
oral
IV

A

oral - oral/vaginal candidiasis

IV - c diff

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6
Q

what does the adaptive immune response involve and what is it

A

B cells
antibodies
T cells
dendritic cells

slow response, responsible for immunological memory

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7
Q

Neutrophils, monocytes, macrophages and dendritic cells are all…

A

phagocytes

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8
Q

phagocytes are an important source of …

A

cytokines

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9
Q

B cells, T cells and NK cells are all …

A

lymphocytes

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10
Q

eosinophils, mast cells and basophils are all …

A

granular cells - release chemicals for acute inflammation

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11
Q

give 2 factors associated with humoral immunity

A

antibodies

complement proteins

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12
Q

where do mast cells reside and what do they do

A

reside in tissues and protect mucosal surfaces

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13
Q

where are basophils and eosinophils located

A

circulate in blood and are recruited to sites of infection

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14
Q

what do basophils, eosinophils and mast cells do upon activation

A

release histamine, heparin, tryptase and pro-inflammatory cytokines

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15
Q

what are basophils, eosinophils and mast cells involved in primarily

A

defence against large anti-body coated pathogens that can’t be phagocytosed e.g. parasitic worms

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16
Q

if a cell is multinucleate it is a …

A

neutrophil

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17
Q

where are neutrophils found

A

circulate freely in blood and are rapidly recruited to inflamed and infected tissue

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18
Q

what are 3 mechanisms by which neutrophils attack pathogens

A

phagocytosis
degranulation - release of antimicrobial peptides and degradative proteases
generate extracellular traps

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19
Q

what do active neutrophils release

A

TNF (pro-inflammatory cytokine)

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20
Q

neutrophils are numerous and short lived

true/false

A

true

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21
Q

neutrophils make use of PAMP recognition and activation

true

A

true

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22
Q

what makes up pus

A

dead and dying neutrophils + tissue cells + microbial debris

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23
Q

what cells are precursors of macrophages

A

monocytes

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24
Q

where are macrophages found

A

reside in tissues

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25
Q

what do macrophages do when active

A

ingest and kill extracellular pathogens

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26
Q

what do macrophages do when neutral

A

clear debris from tissue cells

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27
Q

give 3 other functions of macrophages

A

inflammation
tissue repair and wound healing
antigen presentation

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28
Q

how are macrophages attracted to apoptotic cells

A

apoptotic cells release an ‘eat-me’ signal

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29
Q

what are the 4 stages of phagocytosis

apoptotic cell

A

1) formation of a phagocytic cup around cell
2) pinches off forming a phagosome
3) fusion with lysozyme forms a phagolysosyme - degradation of contents
4) debris released into ECF

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30
Q

what is released along with cellular debris from a phagocyte

A

anti-inflammatory mediators e.g. IL10

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31
Q

what are the 5 stages of phagocytosis of a pathogen

A

1) phagocytic cup around pathogen
2) pro inflammatory stimuli released e.g. LPS, INF-Y
3) this enhances macrophage activation and the production of toxic NOS and RNS
4) pinches off forming phagosome
5) antigen presentation –> activated macrophage

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32
Q

give 3 infections which evade phagosomal killing

A

salmonella
staph aureus
mycobacteria

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33
Q

where are dendritic cells found

A

immature cells in peripheral tissues / tissues with contact to external environment

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34
Q

what do dendritic cells do when they come into contact with a pathogen

A

mature and migrate to secondary lymphoid tissues

stimulate adaptive immune response through antigen presentation

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35
Q

how do dendritic cells become activated

A

phagocytose, process and present antigen on surface to T cells

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36
Q

what do NK cells release

A

pro-inflammatory mediators e.g. IFN-Y

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37
Q

what kind of cells are NK cells

A

large granular lymphocytes

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38
Q

what do NK cells kill

A

tumour and virally infected cells - don’t express MHC class 1 which is present in normal cells to inhibit NK action

can also kill antibody-bound dresses

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39
Q

what do B cells do

A 
produce antibodies (humeral immune response)
which coat pathogens to help phagocytosis
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40
Q

what are the 2 types of T cells

A

helper T cells

cytotoxic T cells

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41
Q

what do helper T cells release

A

CD4+

most people need HELP for T4

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42
Q

what do cytotoxic T cells release

A

CD8+

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43
Q

what do helper T cells do

A

activate other immune cells - receptor:ligand interactions

produce cytokines that help phagocytes kill ingested bacteria

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44
Q

what do cytotoxic T cells do

A

kill virally infected body cells

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45
Q

what is primary lymphoid tissue

A

site of leukocyte development
red Bone marrow and Thymus

(B for B cells) (T for T cells)

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46
Q

what is the function of lymph nodes

A

positioned regularly along lymph vessels - trap pathogens and antigens in lymph

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47
Q

how does lymph move

A

valves and muscle movement

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48
Q

what is secondary lymphoid tissue

A

sites where adaptive immune response is initiated (lymph nodes - tissue infections, tonsils, spleen-blood borne infections)

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49
Q

what are cytokines

A

produced in response to infection, inflammation and tissue damage
they co-ordinate the immune system by modulating cell behaviour
indirect communication

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50
Q

what are 4 examples of cytokines

A

interferons
TNF
chemokines
interleukins

51
Q

what kind of cells produce and release interferons and what is their function

A

virally infected cells
signals neighbouring cells to destroy RNA and reduce protein synthesis and to undergo apoptosis
activates immune cells e.g. NK cells

52
Q

what is the function of IL2 and what is the source

A

T cell proliferation

Th1 cells

53
Q

what is the function of IL10 and what is the source

A

anti-inflammatory - inhibits Th1 cytokine production

Th2 cells

54
Q

what are some s/s of acute inflammation

A 
redness
heat
swelling
pain
loss of function
fever
55
Q

what does the innate immune response involve and what is it

A 
mast cells
NK cells
phagocytes
complement
neutrophils
macrophages

rapid, general response responsible for acute inflammation and killing of pathogen

56
Q

what are the 3 phases of the innate immune response

A

recognition phase (PRRs:PAMPs)
activation phase
effector phase

57
Q

PAMPs are specific to certain pathogens

true/false

A

false

there is a limited number of PAMPs which are common to many different pathogens

58
Q

what are the 2 forms of communication in the immune system and give an example of each

A

1) direct - receptor:ligand
MHC:TCR
PAMP:PRR

2)indirect - production and secretion of cytokines
ILs, interferons, TNF

59
Q

what drives the acute phase response

A

cytokines

60
Q

what organ produces acute phase proteins in response to pro-inflammatory cytokines (IL1, IL6, TNF)

A

liver

61
Q

what are 3 examples of acute phase proteins

A

CRP
complement proteins (C3, C4, mannose-binding lectin)
Serum amyloid A

62
Q

what is the complement system

A

family of proteins produced in the liver that circulate in blood and enter inflamed and infected tissues where they become activated

63
Q

what are the 3 pathways of complement system activation

A

classical
mannose binding lectin
alternative

64
Q

when triggered specific complement proteins can enzymatically activate other complement proteins in cascade
true/false

A

true

65
Q

what is the complement equation

A

C3 —> C3b + C3a

66
Q

what do C3b + C3a do

A

activation of downstream complement proteins

67
Q

what does the activation of downstream complement proteins cause

A

pathogen killing (MAC)
pathogen opsonisation
leukocyte recruitment and inflammation (chemotaxis)
removal of immune complexes

68
Q

how is the mannose-binding lectin pathway stimulated

A

mannose expression unique to certain microorganisms (not expressed on human cells)

69
Q

how is the alternative pathway stimulated

A

spontaneous breakdown of C3

C3b is stabilised on bacterium but degraded on human cells

70
Q

how are C5a and C5a formed

A

C3b causes C5 —> C5a and C5b

71
Q

what complement proteins are involved in leukocyte recruitment and inflammation

what do they do?

A

C3a and C5a

act directly on BVs to increase permeability and therefore increase leakage from blood
activate mast cells/basophils which release pro inflammatory mediators e.g. histamine and chemokines

72
Q

how is the MAC formed

A

C5b binds to surface of pathogen

C6 7 8 and 9 assemble with C5b forming MAC

73
Q

how does the MAC work

A

inserts into target cell walls - osmotic cell lysis of pathogen

74
Q

what is pathogen opsonisation

A

coating of pathogen by humoral factors (opsonins) to facilitate phagocytosis
phagocytes express receptors for opsonins on cell surface

75
Q

what are 4 examples of opsonins

A

C3b
CRP
IgG
IgM

76
Q

complement proteins have a short half life

true/false

A

true

77
Q

only cleaved complement proteins are active

true/false

A

true

78
Q

what traps opsonised cells in B cell zones

A

stromal cells

79
Q

how do T cells recognise a pathogen

A

T cell antigen receptor

  • membrane bound protein heterodimer
  • has alpha and beta chain
80
Q

how do B cells recognise a pathogen

A

B cell antigen receptor

  • membrane bound antibody (IgM or IgD)
  • has a light and heavy chain and disulphide bridges
81
Q

how do lymphocytes find the pathogen

A

secondary lymphoid tissue

82
Q

lymphocytes require 2 signals to be activated

true/false

A

true

83
Q

how are T cells activated

A

MHC/HLA proteins display peptide antigens to T cells

84
Q

what class of MHC/HLA present peptide antigens to cytotoxic T cells (CD8+)

A 
class I
expressed on all nucleated cells
85
Q

what class of MHC/HLA present peptide antigens to helper T cells (CD4+)

A 
class II
expressed only on dendritic cells, macrophages, B cells
86
Q

do B cells need dendritic cells to recognise antigens

A

no - do not need antigen to be presented by MHC

87
Q

what is the name for the immunoglobulins that are produced by B cells in response to an antigen that bind specifically to a single epitope

A

antibodies

88
Q

what do antibodies provide defence against

A

extracellular pathogens - bacteria, viruses, toxins

89
Q

how do the 5 types of antibody differ

A

different Ig heavy chain constant region

90
Q

how are the 2 heavy and the 2 light polypeptide chains held together

A

disulphide bonds

91
Q

what is the most abundant Ig

A

IgG

G for global

92
Q

how does IgG cross the placenta

A

active transport

93
Q

what is the 1st Ig produced during an immune response

A

IgM

IMmediately

94
Q

what Ig is produced in the allergic response

A

IgE

95
Q

what Ig is the 2nd most abundant and found in mucosal secretions

A

IgA

96
Q

what form is IgA in secretions

A

dimer

97
Q

what form is IgA in the blood

A

monomer

98
Q

what Ig can form a pentamer

A

IgM
too big to pass to foetal circulation
M has 5 points on it

99
Q

what region of the Ig is responsible for recognition function

A

variable region

100
Q

what region of the Ig is responsible for effector function

A

constant region

101
Q

where does IgE bind

A

Fc receptor

102
Q

give 5 functions of antibodies

A

agglutination - immune complex formation - aids phagocytosis (IgM and IgG)
opsonins (IgG)
stimulate NK cells (antibody dependent cell mediated cytotoxicity - ADCC) - IgG
trigger allergic reactions
undergo class switching ( switch heavy chain segment) - induced by specific cytokines

103
Q

what can B cells differentiate into

A

plasma cells - effector B cells which produce antibodies

Memory B cells - immunological memory

104
Q

what is the Germinal centre reaction

A

B cell proliferation
antibody heavy chain switching
generation of high affinity antibodies
differentiation into plasma cells and memory B cells

105
Q

how do naive B and T cells enter lymph nodes from high endothelial venules

A

transendothelial migration

- after several days if they don’t encounter specific antigen they return to blood via the efferent lymphatics

106
Q

what is a major source of IL2

A

helper T cells

107
Q

what immune cells mediate acute and chronic organ rejection

A

helper T cells and cytotoxic T cells

108
Q

what immune cells mediate hyperacute organ rejection

A

B cells

109
Q

what is the most common WBC

A

neutrophils

110
Q

what is the main immune cell against protozoan and helminth infections

A

eosinophil
also IgE

E

111
Q

what shape nucleus do monocytes have

A

kidney

112
Q

what cell is a source of IL1 and TNF alpha

A

macrophage

113
Q

Basophils and Mast cells express what receptors on their surface

A

IgE receptors (Fc)

114
Q

what cells release histamine during an allergic reaction

A

mast cells

115
Q

what kind of molecule is IgG

A

monomer

116
Q

what is the most commonly produced Ig

A

IgA

but conc. lower than IgG which is most common

117
Q

what Ig mediates hypersensitivity reactions

A

IgE

118
Q

what is the least abundant Ig

A

IgE

119
Q

what does HIV use to enter a cell

A

CD4

120
Q

what is the co-receptor for MHC class II

A

CD4

121
Q

what is the co-receptor for MHC class I

A

CD8

122
Q

what is the function of TNF alpha/IL1

A

induces fever, neutrophil chemotaxis

123
Q

what is the function of INF gamma

A

activates macrophages

124
Q

what is a source of INF gamma

A

Th1 cells

year 1 (45 decks)

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