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Sem 2 Year 1 > Immunity and inflammation > Flashcards

Immunity and inflammation Flashcards

1
Q

What are the different molecules that mediate immune responses?

A
  • Complement- soluable serum proteins
  • Cytokines and chemokines- messenger hormones
  • Antibodies- secreted molecules which bind pathogens
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2
Q

What are the different types of leukocytes in the innate and adaptive immune processes?

A

Innate= macrophages, dendritic cells, neutrophils, eosinophils, basophils and mast cells

Adaptive= lymphocytes; B and T cells

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3
Q

What tissues are involved in immune response?

A

Lymphatics, lymph nodes, spleen, thymus and bone marrow

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4
Q

Where are immune cells made?

A

Bone marrow and thymus

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5
Q

Where do adaptive immune cells spend most of their time?

A

In lymph nodes and spleen

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6
Q

What is the name given to swelling of lymphatics during infection?

A

Lymphadenopathy

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7
Q

What are primary lymphoid organs?

A

Primary lymphoid organs are where immune cells are made

Immune cells made in bone marrow

T cells mature in the thymus

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8
Q

What are secondary lymphoid organs?

A

Secondary lymphoid organs are where immune responses are initiated

Lymph nodes and spleen

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9
Q

What do virally infected cells release?

A

Virally infected cells release IFN-alpha and IFN-beta (cytokines) which induce an antiviral state in neighbouring states.

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10
Q

What two things does the immune system need to recognise to produce an immune response?

A

Non-self and danger

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11
Q

What are the two types of danger signals?

A

PAMPS= pathogen associated molecular patterns. Molecules only produced by infectious agents e.g. bacterial wall constituents. Critial for survival of pathogen so cannot lose them

DAMPS= damage associated molecular patterns. Molecules released from injured cells such as DNA, RNA, ATP

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12
Q

What are the two types of cell death and what are their differences?

A
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13
Q

How does the innate immune system know what is a pathogen and what is not?

A

Pattern recognition receptors (PRR)

Recognise PAMPs and DAMPs.

They are mainly expressed by antigen presenting cells such as dendritic cells and macrophages, but they are also found in other immune and non-immune cells.

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14
Q

What is an example of pattern recognition receptors?

A

Toll-like receptors

TLR3 binds double stranded RNA from viruses

TLR4 binds bacterial cell wall

TLR5 binds flagellin

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15
Q

What immune response would stepping on a dirty nail cause?

A

Full immune response

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16
Q

What immune response would absorbing food molecules cause?

A

No immune response

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17
Q

What response would a clean scalpel cut cause?

A

Danger= yes

Non-self= no

Innate response only

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18
Q

What immune response would inhaling flu virus cause?

A

Full immune response

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19
Q

What are the main causes of cell injury?

A
  • Lack of oxygen
  • Physical agents such as temperature and radiation
  • Chemicals and drugs
  • Infectious agents
  • Immune reactions
  • Genetic defects
  • Nutrition deficiency
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20
Q

How does apoptosis occur?

A

Apoptosis is usually part of a regulated process, and has been called ‘programmed cell death’ or ‘cell suicide’. It is a carefully regulated event, requiring energy from the dying cell, usually resulting in cell shrinkage and fragmentation. Phagocytosis of the resultant apoptotic bodies ensures there is no associated inflammation and bystander tissue damage.

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21
Q

What are caspases?

A

They cleave aspartate residue, chops up proteins.

Caspase 8 and 9 lead to the executioner caspases such as caspase 3. the caspases chop around all of the intracellular proteins. The nuclear material gets specifically chopped apart- DNA is cut apart between the histones. Very ordered

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22
Q

What is necrosis?

A

Uncontrolled cell death where the cell swells up, the membrane swells up and spillage occurs. Does not require energy to die.

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23
Q

What are the different types of necrosis?

A
  • Coagulative
  • Liquefactive
  • Caseous
  • Gangreous
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24
Q

What is coagulative necrosis?

A

big areas of tissue, no automatic cleanup. The structural proteins of the cells still remain but the nucleus and DNA has degraded. The proteins can glue together and coagulate

There is a ghost outline of cells

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25
Q

What is liquefactive necrosis?

A

Liquefactive= cell protein digested, loss of tissue architecture. There is infiltration by inflammatory cells (neutrophils)- causes pus. There can be a secondary infection by bacteria- wet gangrene. (can use the dead tissue to grow on)

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26
Q

What is caseous necrosis?

A

Granulomas ward off foreign bodies but they cannot degrade. When these collections get bigger and bigger, cells in the middle start to die off.

TB causes this

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27
Q

What are granulomas?

A

Large collections of macrophages,

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28
Q

What are the different types of phagocytes?

A

Neutrophils, macrophages and dendritic cells.

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29
Q

What is the complement system?

A

It is a cascade of soluble proteins and membrane expressed receptors and regulators, which operates in plasma, in tissues, on cell surface, and even within the cell.

It assists the immune system by releasing anaphylotoxins, causing opsonisation of pathogens and forming membrane attack complexes

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30
Q

What are the 3 different complement pathways?

A
  1. Classical
  2. Mannose-binding lectin
  3. alternative pathway
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31
Q

When does the classical complement pathway occur?

A

Only occurs when there are antibodies present specific to a foreign antigen. E.g. on a bacteria. Antibody complexes bound by complement component C1q which then triggers the cascade.

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32
Q

How is the mannose binding lectin complement pathway triggered?

A

Activation through mannose binding lectin binding mannose, or a similar carbohydrates on bacteria. Mannose is not present on the surface of host (human) cell.

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33
Q

How is the complement complement pathway triggered?

A

Most common pathway, based around complement component C3 which is spontaneously activating. When it activates it binds to nearby membrane. Host cells have control proteins on their surface to prevent further complement activation, whilst bacteria cells do not- thus is activates the complement.

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34
Q

What are the 3 ways in which complement helps the immune response?

A
  • Forms membrane attack complexes
  • Mediates anaphylatoxins
  • Causes opsonisation
35
Q

What are membrane attack complexes?

A

They are barrel-like structures that form on membrane of bacteria

Causes water to rush in, and ions to rush out causing the bacteria to swell and burst

36
Q

How does the complement pathway help immune response through anaphylatoxins?

A

Soluable compenent complements are released on complement activation known as anaphylotoxins.

Their release results in blood vessels becoming leaky, causing oedema and allows recruitment of immune cells

37
Q

What is opsonisation?

A

Where bacteria is coated to make it visisible to innate immune cells.

It encourages phagocytosis and killing

38
Q

What are the differences between neutrophils, macrophages and dendritic cells?

A
39
Q

What is the process of neutrophils moving from the circulation to the site of inflamation called?

A

Extravasation

40
Q

How do neutrophils move from blood vessels to tissue?

A

During inflammation local inflammatory cytokines are released- this alters the endothelium of blood vessels and the junctions between cells become leaky.

Neutrophils start to roll along the endothelium, then firmly adhere and exit between endothelial cells (diapedesis). They follows a chemokine gradient to the site ofinflammation.

41
Q

What is the pathogen called when a phagocyte engulfs it?

A

Phagosome

42
Q

What happens when lyosomes fuse with phagosome and what is it called?

A

Lysosomes fuses with a phagosome and the toxic products kill/ degrade the pathogen

Called a phagolysosome

43
Q

How are macrophages activated?

A

Activation can come from danger signalling or cytokines, especially IFN gamma

44
Q

What is netosis?

A

Neutrophils can extrude their DNA, acting like a net which traps pathogens that it is struggling to kill.

45
Q

What is antigen specificity?

A

Antigen= a molecule that is recognised by the adaptive immune system. Adaptive immune cells are randomly generated to express a unique receptor which recognises a specific antigen

Antigens can be self or non-self

46
Q

Why do dendritic cells migrate to lymph nodes?

A

When they are in the periphery they are constantly taking up antigens. If they sense danger they mature.

They upregulate different chemokine receptors

This results in their migration to the lymphatics and into the draining lymph node, where they will present the antigen to lymphocytes.

47
Q

What cell do dendritic cells present their antigen to?

A

T cells

48
Q

How doe B cells and T cells recognise antigen?

A

The B cell receptor BcR can recognise soluble antigen in its normal for,

The T cell receptor TcR has to have antigen ‘presented’ to it on the major histocompatibility complex. Antigens must be chopped up into peptides which are then loaded onto MHC molecules and presented on the surface of the cell

49
Q

What signals do dendritic cells need to give to activate T cells?

A

Signal one= MHC + antigen

Signal 2= costimulation

50
Q

What will happen to a T cell if there is no stimulation singal from dendritic cells?

A

Anergy/death

Anergic= they cannot be activated again

51
Q

What is the third signal from dendritic cells to activate T cells?

A

The third signal is a release of cytokines which tells T cells what type of cell to become.

52
Q

What is inducible immunity?

A

An alert response to mounting danger that disrupts and damages tissue. Caused by:

PRRs over a threshold, triggering inflammtion

Antigen specific receptors after an antigen encounter tigger adaptive immunity

53
Q

What are the main factors that maintain immune health?

A

Physical activity

Sleep

Microbiota

54
Q

How does having healthy skeletal muscle moderate immunity?

A

Skeletal muscle is a major source of cytokines in homeostasis.

Myokines support immunity and regulate inflammation, also causes adaptive responses to new and recall antigens in the elderly and causes innate functions such as boosting NK and macrophages.

55
Q

What are tissue-resident sentinel cells and sentinel cells?

A

Tissue resident monitor near surfaces like skin and GI mucosa- mast cells, macrophages, dendritic cells

Sentinel cells monitor inside blood vessels- monocytes, NK cells

56
Q

What is the decline of immunity that comes with older age called?

A

Immunosenescence

57
Q

Why does the immune system decrease in old age?

A

Thymus and marrow atrophy reduced lymphocyte diversity

DNA methylation reduces survival factor for memory cell generation

Exhausted T cells from chronic infection

Scars from severe infection

58
Q

What is inflammaging?

A

It is chronic low grade inflammation which lasts for decades and contibutes to age-related multisystem morbidity e.g. atheroma.

59
Q

What is metaflammation?

A

Inflammation in metabolic disease

60
Q

How can does type II diabetes arise from obesity?

A

Nutrient stress (volume/quality in obesity) causes mitochondrial dysfunction with increased oxidative stress

The stressed adipocytes release more inflammatory cytokines (danger signals) such as pro-inflammatory adipokines. This causes an influx of inflammatory monocytes and T cells, a senescent immune cell accumulation and adipokines cause insulin resistance in myocytes- poor glucose control.

61
Q

In the intenstine, what secrete mucous?

A

Goblet and Paneth

62
Q

What are the causes of inflammatory bowel disease?

A

Dysfunctional barriers, dysbiosis and inflammation

Genetic/ environmental factors alters the ecosystem subtly. Reduced diversity plus the accumulation of a microbes causes inflammation.

Once there is inflammatory damage, causes danger signals which causes a breakdown of barrier and recruitment of other immune cells.

63
Q

What is dysbiosis?

A

A disruption to the microbiota homeostasis caused by an imbalance in the microflora

64
Q

What are the two different cell metabolic programs?

A

Dormancy associated- catabolic

Growth associated- anabolic

65
Q

What are catabolic state cells?

A

Cells not directly involved in defence

They are resource converting- maximising energy yield from carbon resources such as glucose

66
Q

What are anabolic cells?

A

Activated immune and repiar cells that are resource demanding. They are involved in proliferation, differentiation and pathogen clearance

67
Q

What is the name given to cells allocating resources for defence and survival?

A

Immunometabolism

68
Q

What is the central hub for switching between anabolic and catabolic states?

A

Mitochondria of the cell

Metabolic reprogramming is signalled by oncogene proteins

69
Q

How does T cell metabolism change during immune response?

A

In a naïve T cell there is only a basal nutrient uptake to sustain itself. Very little biosynthesis is occuring. After activation there is a ramp up of glycolysis and nutrient uptake- switches itself to require glucose fuel. The mitochondria is no longer burning fuel but are exporting intermediates to produce biomass- cell proliferation and growth.

Once the stimulus that activated these cells is finished, they return to quiescence- slightly different to that of naïve cells- more mitochondrial mass- better able to respond faster the next time

70
Q

What are the symptoms of acute inflammation?

A

Swollen, warm, painful, red and loss of function

71
Q

What happens when innate immune cells recognise danger signals from PAMPs and DAMPs?

A

The signals converge and inflammatory cytokines and chemokines, type I interferon is released and there is cell death

72
Q

What are the changes in the small blood vessels that drive inflammation?

A
  • dilitation of the arterioles
  • water uptake into connective tissue matrix
  • junction breaks between endothelial cells
73
Q

What changes neutrophil’s cell adhesion molecule expression?

A

Circulating neutrophils near injured tissue are activated by DAMP or cytokines and chemokines from DAMP activated cells.

74
Q

What causes the endothelial cells to exposure adhesion molecules?

A

Histamine, DAMPs and cytokines such as TNF and IL-1 cause endothelium to shed glycoalyx and exposure sticky adhesion molecules e.g. selectins on its surface.

75
Q

What guides out transmigrating neutrophils?

A

Pericytes

76
Q

What seals the transmigration site of a neutrophil?

A

Platelets

77
Q

What is chemotaxis?

A

Orientation or movement of an organism or cell in relation to chemical agents.

78
Q

What attracts neutrophils to site of injury?

A

SELF= coagulation products, complement and IL-8

NON-SELF= bacterial endotoxins

79
Q

How do resident macrophages stop neutrophils from causing inflammtion in minor damage?

A

Minor damage is cloaked by resident macrophages and so is concealed from neutrophils

80
Q

How does oedema reduced local immunity in tissue?

A

It is harder for immune cells to patrol the extravascular tissue when the connective tissue fibres are seperated by fluid- they need something to adhere to for patrolling tissues

81
Q

What is exudate and gangrene?

A

Exudate is fluid that leaks out of blood vessels into nearby tissues

Gangrene is a dangerous and potentially fatal condition that happens when the blood flow to a large area of tissue is cut off

82
Q

Why does fever occur?

A

Pyrogens can bind to receptors in the hypothalamus, increasing temperature

Once pyrogen is IL-1 produced by macrophages

83
Q
A

Sem 2 Year 1 (12 decks)

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