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Immunology > Introduction to immunity and adaptive immunity > Flashcards

Introduction to immunity and adaptive immunity Flashcards

1
Q

Give features of the innate immune system

A 
non-specific
primitive
instinctive/un-leanred
1st line of defence
provides barrier to antigen
is present from birth
no long lasting memory
does not depend on immune recognition by lymphocytes 
APCs
phacogytosis
complement 
NK cells
PAMPs, PRRs
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2
Q

Give features of the adaptive immune system

A 
aquired immunity
requires lymphocytes and antibodies
response specific to antigen 
B cells and T cells 
memory cells 
Th an d Tc cells 
cytokines
self/non-self recognition
quick response (secondary)
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3
Q

Which cells are polymorphonuclear leukocytes?

A

neutrophils
eosinophils
basophils

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4
Q

Which cells are mononuclear leukocytes

A

T cells
B cells
monocytes

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5
Q

What do the primary granules of neutrophils contain?

A

myeloperoxidase, muramidase, acid

hydrolases, proteins (defensins)

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6
Q

What do the secondary granules of neutrophils contain?

A

lactoferrin and lysozyme

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7
Q

What do the lysosomes of monocytes contain?

A

peroxidase

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8
Q

What is the role of macrophages?

A
  1. remove anything foreign or dead/tumour cells
  2. link the adaptive and innate immune system through antigen presentation to T cells via phagocytosis
  3. destruction of bacteria through phagocytosis
  4. first line of non-self recognition
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9
Q

What kind of receptors do macrophages have on their surface?

A 
Fc receptors
complement receptors 
PRRs
TLRs
mannose receptors
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10
Q

What do eosinophil granules contain?

A

major basic protein - potent toxin for helminth worms, activates neutrophils and induces histamine release from mast cells

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11
Q

What receptors do basophils have on their surface?

A

high-affinity IgE receptors (FcεR1)

:)

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12
Q

What is the main role of basophils?

A

immunity to parasitic infections and allergic reactions (like eosinophils and mast cells, but mast cells are only in the tissues)

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13
Q

What is CD3?

A

T cell receptor complex

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14
Q

What is the Th1 response?

**** intracellular Th1 and extracellular Th2 - or both extracellular need to as lecturer *****

A

HELPS KILL INTRACELLULAR PATHOGENS -responds to intracellular pathogens eg viruses and also bacteria, production of IgG, macrophages activated, CD4 and MHC II, IL-12. activate naive T cells to Th1 cells, activated Th1 cells proliferate (clonal expansion). Th1 cells secrete INF-gamma to stop virus spread and apoptosis

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15
Q

What is the Th2 response?

A

Ab PRODUCTION -(help B cells make Ab) responds to extracellular pathogens eg parasites and allergens and produces IgE, CD 4 and MHC II involved, IL-4, IL5, IL -10and INF-gamma. CD4 and MHC II involved.

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16
Q

Describe cytotoxic T cells

A

CD8, can kill cells directly eg cancer cells and virus infected cells. express T Cell Receptors that can recognise a specific antigen,
formation of perforin (apoptosis) and granulysin (killing of pathogen)

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17
Q

Where are T cells found?

A

blood, lymph nodes, spleen

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18
Q

What do B cells do in the adaptive immune response?

A
  1. recognise antigen displayed by APCs
  2. express membrane bound antibody
  3. differentiate into plasma cells that make Ab
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19
Q

What do natural killer cells do?

A

express CD56
can recognise and kill virus infected cells and tumour cells by apoptosis (perforin forms pores in the cell membrane which induces apoptosis)

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20
Q

what is the significance of CD4 and CD8?

A

In order for the TCR to bind to the antigen bound to MHC, the TCR must be accompanied by CD8 or CD4 which bind to a different part of MHC

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21
Q

Give examples of soluble factors involved in immunity

A

complement
antibodies
cytokines
chemokines

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22
Q

how are each of the pathways activated in the complement cascade?

A

classical - antigen antibody complexes
alternative - bacterial cell walls and endotoxin, complement binds to microbe
lectin - activated by circulating mannose binding lectin that binds to carbs on the surface of microbes

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23
Q

What is an antibody?

A

A specific protein produced in response to an antigen

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24
Q

What is an antigen?

A

a molecule that induces an immune response (from lec it says a molecule that reacts with preformed antibody an d specific receptors on T and B cells)

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25
Q

What is an epitope?

A

part of the antigen that binds to the antibody binding site

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26
Q

What does affinity mean in the context of antibodies?

A

a measure of binding strength between an epitope and an antibody binding site

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27
Q

What is the basic structure of an antibody?

A

2 heavy chains
2 light chains
Fab region where the antigen binds
Fc portion where the antibody that interacts with cell surface receptors (Fc receptors on phagocytes, nK cells etc) and proteins of the complement system
has a hinge, so that the arms of the Ab can reach to get to antigens

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28
Q

Give features of IgG

A

most abundant antibody in the serum
especially important in the secondary immune response
crosses the placenta

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29
Q

Give features of IgM

A

pentamer - requires Joining chain
mainly found in blood
large so cannot cross the endothelium (or placenta)
primary response and initial contact with antigen
the monomeric form is present as a receptor on B cells

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30
Q

Give features of IgA

A

dimer joined by Joining chain
in mucous secretions eg saliva, colostrum, milk, bronchiolar and GU secretions
secretory component prevents digestion by enzymes

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31
Q

Give features of IgE

A

basophils and mast cells express the high affinity IgE receptor and so are continually saturated with it
triggers release of histamine when antigen binds
allergy + parasites

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32
Q

Name some of the key cytokines

A

interferons
interleukins
colony stimulating factors
tumour necrosis factor alpha and beta

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33
Q

What do interferons do?

A

induce antiviral resistance in unifected cells and so limit the spread of viral infection

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34
Q

What are interferons produced by?

A

virus infected cells and activated Th1 cells

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35
Q

What do interleukins do?

A

pro-inflammatory IL1
antiinflammatory IL10,
cause cells to divide, differentiate and secrete factors

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36
Q

What do colony stimulating factors do?

A

direct the division and differentiation of bone marrow stem cells matching the demand

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37
Q

What does TNF do?

A

mediates inflammation and cytotoxic reactions

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38
Q

What do chemokines do?

A

direct the movement of leukocytes and other cells from the blood stream into the tissues or lymph organs by binding to specific receptors on cells

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39
Q

Which cells originate from myeloid progenitors?

A 
erythrocytes
platelets
monocytes + macrophages 
neutrophils
eosinophils
basophils
40
Q

Which cells originate from lymphoid progenitors?

A

B cells
T-reg
T-helper
Cytotoxic T cells

41
Q

What does innate immunity comprise of?

A
  1. physical and chemical barriers
  2. phagocytic cells (neutrophils and macrophages)
  3. serum proteins (complement, acute phase)
42
Q

Give examples of physical barriers used by the innate immune system

A 
skin 
lysozyme in tears and other secretions
mucus and cilia in bronchi
acid in the stomach
commensals in the gut
low pH and commensals of vagina
saliva
43
Q

describe the skin as a barrier

A

dermis and epidermis

sebum (skin secretions at pH 3-5)

44
Q

Give examples of physiological barriers

A

temperature - fever inhibits microbe growth
pH
oxygen tension - affecting growth of aerobes or anaerobes

45
Q

Give some responses of the body during inflammation

A 
coagulation 
acute inflammation
kill pathogen
neutralise toxins
phagocytosis
proliferation of cells to repair damage
removal of blood clot
46
Q

What is inflammation?

A

A series of reactions that brings cells and molecules of the immune system to sites of infection or damage

47
Q

What are the hallmarks of imflammation?

A

increased blood supply
increased vascular permeability
extravasation

48
Q

Define acute inflammation

A

Complete elimination of a pathogen followed by resolution of damage, disappearance of leukocytes and full regeneration of tissue

49
Q

define chronic inflammation

A

persistent unresolved inflammation

50
Q

which cells detect microbes in the blood?

A

neutrophils and monocytes

51
Q

Which cells detect microbes in the tissues?

A

macrophages and dendritic cells

52
Q

What do TLRs do?

A

recognise PAMPs expressed by microbes

53
Q

What can complement achieve?

A
  1. lysis of microbes e.g. with the MAC
  2. increase chemotaxis (c3a, C5a)
  3. opsonisation (C3b)
54
Q

What two chemicals play a large role in extravasation of neutrophils?

A
  • cytokines i.e. TNF alpha

- chemokines

55
Q

What substances destroy pathogens in a phagolysosome?

A
  1. O2 dependent - ROS e.g. superoxide, H2O2 and OH radical, NO
  2. oxygen independent - defensins, lysozyme, pH, TNF
56
Q

Give examples of acute phase proteins

A

CRP
Mannose binding lectin
Surfactant protein A

57
Q

What is CRP?

A

C reactive proteins - serum protein produced by the liver and binds to some bacterial cell walls to promote opsonisation as well as activating complement

58
Q

What is mannose binding lectin?

A

binds to lectin on microbes and promotes opsonisation and activates complement

59
Q

what does surfactant protein A do?

A

binds to haemaglutinin in influenza - reduces the ability of virus to infect cells

60
Q

Why do we need the adaptive immune response?

A
  1. microbes can evade innate immunity (proteases and decoy proteins)
  2. need memory to specific antigen
  3. intracellular bacteria and viruses hide from innate immunity
61
Q

Which lymphocyte is involved in cell mediated immunity?

A

T cell

62
Q

which lymphocyte is involved in humour immunity?

A

B cell

63
Q

Give examples of secondary lymphoid tissue

A

spleen
lymph nodes
MALT

64
Q

give examples of primary lymphoid tissue

A

bone marrow

thymus

65
Q

give examples of antigen presenting cells

A

Dendritic cells Macrophages B cells

66
Q

What two cell types does cell mediated immunity involve?

A

T cells

APCs

67
Q

Give two roles of cell mediated immunity

A
  1. control antibody production via contact with B cells

2. directly recognise and kill virus infected cells

68
Q

What is T cell selection?

A

T cells that recognise self antigens are killed in the foetal thymus as they mature

69
Q

What does an antigen have to be presented with for a T cell to recognise it?

A

Major histocompatibility complex

70
Q

What does MHC and the antigen bind to in the adaptive immune response?

A

T cell receptor

71
Q

What type of T cells recognise MHC I?

A

cytotoxic T cells

72
Q

What type of T cells recognise MHC II?

A

T helper cells

73
Q

What type of cells is MHC I present on?

A

ALL nucleated cells

74
Q

What type of cells is MHC II present on?

A

APCs only

75
Q

What molecule do T helper cell use to enhance binding to MHC?

A

CD4

76
Q

What molecule do cytotoxic T cells use to enhance binding to MHC?

A

CD8

77
Q

What type of antigen is associated with an MHC I response?

A

intracellular antigen e.g. virus

78
Q

What type of antigen is associated with an MHC II response?

A

extrinsic antigen (i.e. both the Th1 and the Th2 response)

79
Q

What is the result of an MHC I response?

A

KILLING of infected cell with INTRACELLULAR pathogen

80
Q

What is the result of an MHC II response?

A

ANTIBODIES

Help B cells make Ab to EXTRACELLULAR pathogen and can help directly kill (apoptosis)

81
Q

What molecules are required for T cell recognition and activation?

A
  1. co-stimulatory molecules e.g. CD28 on T cell binds to CD80/86 on APCs
  2. IL-2 autocrine secretion
  3. MHC
  4. CD4/8
  5. antigen
  6. TCR bound to CD3
82
Q

Which cytokines are associated with a Th1 response?

A

IL-2
IFN-gamma (stops virus spread and apoptosis)
(TNF beta)- from other lady lec

83
Q

Which cytokines are associated with Th2 response?

A

IL-4
IL-5
IL-10
(IL-6, IL-13) - from other lady lec

84
Q

What type of Ig is on the surface of B cells?

A

IgM and IgD

85
Q

How specific is a B cell?

A

Only makes one Ab that can only bind to one epitope of an antigen

86
Q

What molecule do B cells present antigen with?

A

MHC II (remember this class is only on APCs)

87
Q

Explain how clonal expansion occurs from APCs and naive T cells to plasma cells

A
  1. APC phagocytosis and Ag presentation
  2. Ag presented to naive T cells
  3. naive T cells turn into Th2 cells
  4. TH2 cells secretes cytokines e.g. IL-4, IL-5, IL-10
  5. causes B cells to divide by clonal expansion in lymph nodes
  6. plasma cells and memory cells are produced from differentiation of B cells
88
Q

Where does clonal expansion of B cells occur?

A

Lymph nodes

89
Q

What are the 3 main functions of Ab?

A
  1. neutralise toxin
  2. increase opsonisation –> phagocytosis
  3. activate complement
90
Q

How are antibodies that bind different epitopes made?

A

the variable region exons mutate and recombine during B cell differentiation

91
Q

name antibodies involved in the secondary response

A

mainly IgG but also IgA and IgE

92
Q

How are antibodies used in research, diagnostics and therapy?

A
  1. identify and label molecules in tissues
  2. serotype pathogens
  3. identify cell types
  4. humanised antibodies
93
Q

How do TCRs on T cells recognise different antigens?

A

exons of variable regions of the TCR recombine during T cell differentiation

94
Q

Give a disease in which MHC is involved

A

graft rejection

95
Q

How do cytokines act?

A

bind to cytokine receptors on the surface of target cells

96
Q

What is the hygiene hypothesis?

A

insuffienct exposure to certain infections skews the Th1/2 balance towards Th2 therefore infection protect against allergy

97
Q

Describe what happens at the lymph nodes

A

APCs enter the lymph node and activate T cells and B cells to produce effector T cells and plasma cells and Antibody which leave the lymph node. Naive T cells enter the lymph node and are converted to these effector T cells

Immunology (4 decks)

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