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MCD > Immunology > Flashcards

Immunology Flashcards

1
Q

What is SCID

A

Severe combined immunodeficiency

Increases infection susceptibility

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2
Q

Summarise basic strategy 1

A

Recognition of molecular patterns
Hundreds of receptors
Germ-line encoded

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3
Q

What are the advantages and disadvantages of basic strategy 1

A

Many cells can express the same receptor for a rapid + effective response
Limited receptor diversity, some pathogens may not be efficiently recognised

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4
Q

What does basic strategy. 1 use

A

Pattern recognition receptors with 2 triggers: pathogen associated molecular patterns (PAMPs) or damaged associated molecular patterns (DAMPs)

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5
Q

Summarise basic strategy 2

A

Recognition of precise structures
Millions of receptors
Generated by random recombination of gene segments

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6
Q

What are the advantages and disadvantages of basic strategy 2

A

Massive diversity of receptors, all structures may be potentially recognised
Cells must be greatly expanded to generate an effective response, long time for this, random nature may cause autoimmunity

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7
Q

What is the epitome

A

The area on antigen to which antigen receptors bind to

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8
Q

Compare and contrast innate and adaptive immunity

A

Independent of previous exposure vs adaptation to exposure
Depends on pre-formed components vs depends on clonal selection
Fast vs slow
Limited specificity vs highly specific

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9
Q

What does innate immunity involve and which interferon is associated

A

Destroys invading nucleic acids
Activates inflammatory pathways and signals
Promotes and directs adaptive response + buys time for it
Type 1 interferon

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10
Q

What does adaptive immunity involve

A

Memory cell formation

Cellular and humeral response

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11
Q

What proportion of circulating WBCs do lymphocytes make up

A

20-40%

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12
Q

Which cells and substances are used in innate response

A 
Neutrophils
Macrophages
Eosinophils
Complement
Actue-phase P
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13
Q

Which cells and substances are used in innate and adaptive response

A

Basophils
Dendritic cells
Natural killer cells
Cytokines

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14
Q

Which cells and substances are used in adaptive response

A

T lymphocytes
B lymphocytes
Antibodies

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15
Q

Outline the process of clonal selection

A

Polyclonal naive lymphocyte
Activation
Proliferation
Effector lymphocyte

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16
Q

What may occur when the antigen is removed

A

Lymphocytes die while some survive as memory cells

On re-exposure, there is a quicker and greater response

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17
Q

How is diversity of immunoglobulin and TCR generated

A

Genetic recombination

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18
Q

What is the difference between primary and secondary lymphoid organs

A

primary is where lymphocytes are produced, secondary is where lymphocytes interact with antigens

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19
Q

Give examples of primary lymphoid organs

A

Thymus

Bone marrow

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20
Q

Give examples of secondary lymph organs

A

Lymphatic system
Lymph nodes
Spleen
Epithelium/cutaneous

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21
Q

Describe the structure of the thymus

A

Bi-lobed
Packed with proliferating lymphocytes
Medulla and cortex

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22
Q

What happens to the thymus during infection

A

No obvious change

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23
Q

What are Hassall’s corpuscles and where are they found

A

Fibroblasts for regulatory T cell development found in the thymus

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24
Q

What happens to the thymus with age

A

Decrease in output of new lymph (but total does not decrease)

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25
Q

Describe the bone marrow

A

Site of B cell and RBC production

Yellow fat surrounded by red marrow

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26
Q

What happens in the bone marrow during infection

A

Increase in white blood cell production

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27
Q

Describe the lymphatic system

A

Drainage system to collect antigens and filter through the nodes and return fluid to the blood
Antigen is likely to enter the lymphatic system

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28
Q

Draw/describe a lymph node

A

Kidney shape
Medullary sinus is surrounded by the T cell area with many germinal centres surrounding this
Lymphoid follicle surrounds this

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29
Q

What is a germinal centre

A

Area where B cell proliferate

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30
Q

What happens to the lymph nodes during infection

A

Lymph nodes become enlarged/swollen

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31
Q

What is the purpose of high endothelial venues and where can they be found

A

causes cells to move from the blood to lymph

Found in the lymph nodes

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32
Q

Which secondary lymphoid organ does not have many HEV

A

Spleen

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33
Q

What is the function of the spleen

A

Filters for antigens in the blood

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34
Q

Describe the structure of the spleen

A 
White pulp (WBC)
Red pulp (RBC)
Germinal centres
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35
Q

What happens to the spleen during infection

A

Larger follicles

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36
Q

Describe how epithelium is a secondary lymphoid organ

A

Mucosal and skin as a physical barrier
Mucosae-associated lymphoid tissue (MALT)
Lymph drains in villi

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37
Q

What are Peyer’s patches and where are they found

A

Large aggregates of B cells that contain germinal centres important for immune response found in the gut epithelium

38
Q

What are microfold cells and where are they found

A

Cells that sample antigens to pass them to the Peyer’s patch in the gut

39
Q

Which immune response cells are found in the skin

A

Epidermal langerhans cells
T lymphocytes
Macrophages
Dermal dendritic cell

40
Q

How is it ensured that antigen meets the lymphocyte with the specific receptor

A

re-circulation

41
Q

Describe the process of extravasion

A
  1. Naive T cells rolls along the endothelium
  2. They bind to proteins and carbs along the epithelium
  3. HEV has chemokine bound to the cell surface
  4. Lymphocytes have receptors for this and binds to the receptor
  5. Lymphocytes deliver a signal to the T cell, changing the structure of integrin
  6. Integrin becomes high affinity binding and binds to the epithelium to stop movement
  7. Transport through epithelium
42
Q

How do you distinguish between B and T cells

A

Cluster differentiation (CD) markers - use of antibodies

43
Q

How much of the total pool of T cells is contained in the blood

A

2%

44
Q

Which CD marker do T cells express

A

CD3

45
Q

What are the two types of T cell receptor

A

gamma delta - 10%

alpha beta - 90%

46
Q

What are the proportions of CD4 and CD8

A

2/3 CD4

1/3 CD8

47
Q

Which cells present CD4 and CD8

A

CD4 - T helper and regulatory cells that secrete cytokines

CD8 - Cytotoxic T cells that lyse infected cells that secrete cytokines

48
Q

Which CD markers do B cells express

A

CD19 and CD20

49
Q

Give a difference in the way B cells and T cells recognise antigens

A

T cells recognise processed antigens

B cells recognise “intact” antigens (unprocessed)

50
Q

What are the antigen presenting cells

A

Dendritic cells
B lymphocytes
Macrophages

51
Q

What does innate mean

A

inbuilt

Uses cellular and soluble components

52
Q

Give the physiological barriers

A

Skin - acidic

mucous membranes + cilia

53
Q

Give some physiological barriers

A

body temperature - during fever the high temp is not favourable
low pH - acidic to kill
Lysosome, interferons, complement

54
Q

Describe a neutrophil

A 
Phagocytosis
40-75% of leukocytes
short-lived
circulates the blood
First cells recruited
55
Q

Describe the process of neutrophil travels through a membrane

A
  1. neutrophil rolls along the membrane
  2. infection releases chemokines
  3. chemokines bind to the endothelial cell surface
  4. Neutrophil recognises the signal and increases its affinity to bind to the membrane
  5. passes through diapedesis
56
Q

Which cells present CD4 and CD8

A

CD4 - T helper and regulatory cells that secrete cytokines

CD8 - Cytotoxic T cells that lyse infected cells that secrete cytokines

57
Q

Define opsonisation

A

coating of micro-organisms with proteins for phagocytosis

Antibodies and complement function by this

58
Q

What are NETs

A

neutrophil extracellular traps

Release of granules and chromatin to form extracellular fibres

59
Q

Describe eosinophils

A

phagocytosis and granule release
Defence against parasites
Helps B cells in GALT (IgA production)

60
Q

Describe basophils

A

Granule release

Acts as an APC for type 2 immunity

61
Q

Describe monocytes

A

phagocytosis , killing, cytokine release, APC
less abundant
dispersed in tissue
Signal infection to soluble mediators
Become macrophages when the leave the blood

62
Q

Describe mast cells

A

Phagocytosis, granule release (pro-inflammation), histamine and leukotrienes
Mucosal in the lung or connective tissue in the skin
Activation by complement products (anaphylatoxins)
vasodilation (red skin) and increased vascular permeability (inflammation)

63
Q

Describe dendritic cells

A

APC and cytokine secretion
migration to lymph node
network site of infection
adaptive

64
Q

Describe natural killer cells

A

10% of blood
Infected cell lysis, secretion of interferon gamma, activating and inhibitory receptors (NO antigen receptor), binds to opsonised cells
Large granulated lymphocytes (cytotoxic)
Bind to opsonised cells
Cancer and viral infections

65
Q

What are soluble mediators

A

Small secreted proteins important in cell-cell communication that are generally local acting
Effective even in low concentration

66
Q

What are the types of soluble mediators and what are their functions

A 
Interleukins - leukocyte communication
Interferons - anti-viral
Chemokines - chemotaxis
Growth factors - proliferation and differentiation
Cytotoxic - tumour necrosis factor
67
Q

What is complement

A

Complex series of 30 proteins and glycoproteins
Major role in complimenting the activity of specific antibodies in lysing bacteria
Triggers enzyme cascade systems to give a rapid and highly amplified response

68
Q

What is complement produced by

A

The liver as inactivated precursors

69
Q

How is complement activated

A

Cleavage of the end
Classical pathway
Lectin pathway
Alternative pathway

70
Q

What do all of the complement activation pathways lead to

A

Activation of C3b

Membrane attack complex (MAC)

71
Q

Describe the activation pathways for complement

A

Classical - activation by antibodies
Lectin - lectin proteins that bind carbohydrates
Alternative - bacterial surface directly activate the complement

72
Q

Define antibody

A

Protein produced in response to antigens

73
Q

What are immunoglobulins

A

Classes of antibodies
Large family of glycoproteins
>107 antibodies
produced by B lymphocytes

74
Q

What are the secondary effector functions of immunoglobulins after binding

A

Complement activation
Opsonisation (promotion of phagocytosis)
Cell activation via antibody-binding receptors (Fc receptors)

75
Q

Describe the structure of immunoglobulins

A 
2 heavy chains and 2 light chains held together by disulphide bonds 
Symmetrical 
Hinge region 
constant region - Fc
variable region - Fab
76
Q

What are hyper variable regions

A

there are 3 in antibodies: CDR 1,2,3)

CDS = complement determining regions that acts as binding sites for antigens

77
Q

What is the immunoglobulin super family

A

similar domain to antibodies

78
Q

Give the forces involved in antigen-antibody binding

A

H-bonds
Ionic bonds
Hydrophobic interactions
Van der Waals

79
Q

Define antibody affinity

A

The strength of the total noncovalent interactions between a single antigen binding site and a single epitope on the antigen

80
Q

Define antibody avidity

A

The overall strength of multiple interactions between n antibody with multiple binding site and a complex antigen with multiple epitopes

Better measure of binding capacity

81
Q

Define antibody-cross reactivity

A

Antibody elicited in responses to one antigen can sometimes recognise a different antigen of a different structure

82
Q

Give examples of antibody-cross reactivity

A

Vaccination with cowpox induces antibodies which are able to recognise smallpox
ABO blood group antigens
Antibodies made against Microbial antigens on common intestinal bacteria may cross-react with carbs on RBC

83
Q

What differs between the different classes of immunoglobulin

A

heavy chains

84
Q

Describe IgG

A 
gamma heavy
Most abundant
Has 4 subclasses
Actively transported across the placenta
Major activator of the classical complement pathway (1&3)
Blood and extracellular fluid
85
Q

Describe IgA

A 
alpha heavy
2nd most abundant
2 subclasses
Occurs as a monomer or dimer
secretory 
Protects mucosal surfaces from pathogens
Across epithelia
86
Q

Describe IgM

A 
Micro heavy
First Ig synthesised after exposure
Multiple low affinity binding sites
Large pentamer
Agglutination and complement activation
Blood
87
Q

Describe IgE

A 
E heavy
Allergic reactions
Parasitic infections
Binds to mast cell receptors and basophils to release histamine
Very low levels
88
Q

Describe IgD

A

Delta heavy
Expressed in B cell development and activation
very low levels

89
Q

Give the actions of antibody-antigen

A 
Neutralisation
Agglutination
Opsonisation
Complement activation
Bound by cells expressing Fc receptors (innate immunity: phagocytes, NK cells)
90
Q

What are the uses of antibodies defence

A 
Targeting of ineffective organisms
Recruitment of effector mechanisms
Neutralisation of toxins
Removal of antigens
Passive immunity in the new born
91
Q

What are the uses of antibodies in medicine and in labs

A

Levels used in diagnosis and monitoring
Pooled antibodies for passive therapy/protection
Monoclonal antibodies for treatment of cancer

Vast range of diagnostic and research applications

MCD (13 decks)

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