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My Principles > Immunology > Flashcards

Immunology Flashcards

Revision of immunology from principles

1
Q

What is the immune response divided up into?

A
  • Innate/ natural: natural barriers, soluble components and cellular components
  • Acquired/ adaptive: humoral (B cells) and cell-mediated (T cells)
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2
Q

What are the main barriers to infection?

A
  • Skin
  • Mucous
  • Commensal bacteria
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3
Q

How does the skin provide a barrier to infection?

A
  • physical barrier= highly keratinised, multi-layered
  • physiological factors= low pH, low oxygen
  • sebaceous glands= hydrophobic oils, lysosomes, ammonia, antimicrobial peptides
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4
Q

How does mucous provide a barrier to infection?

A

lines resp, GI and urogenital surfaces

  • physical barrier
  • secretory IgAP: prevents bacteria and viruses penetrating epithelial cells
  • enzymes: lysosomes, defensives and antimicrobial peptised
  • cilia
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5
Q

How does commensal bacteria provide a barrier to infection?

A
  • symbiotic relationship
  • makes vitamins K and B12
  • makes bactericides
  • low pH
  • compete for nutrients
  • make anti-microbial fatty acids
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6
Q

What are the main components of the innate immune system?

A
  • leukocytes:phagocytic white blood cells, macrophage, neutrophil, natural killer cells
  • complement: destroys cells
  • inflammatory response: increase temperature, capillary permeability and attract macrophages
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7
Q

What do natural killer cells do?

A

release perforin, forms pores so fluid moves in and out, cell lysis and apoptosis

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8
Q

What does the complement system do?

A
  • attacks bacteria a fungus
  • forms a membrane attack complex
  • perforates cells to cause apoptosis
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9
Q

What does the inflammatory response do?

A
  • releases histamines and prostaglandins
  • capillaries dilate and become leaky (macrophages, RBCs, platelets and clotting factors)
  • increased temperature (decreased bacterial growth, phagocytosis and increased repair)
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10
Q

What is the innate immune system?

A

present continuously and from birth

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11
Q

What is the adaptive immune system?

A

induced by the presence of foreign material and is specific

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12
Q

What are the main specific cells of the innate immune system?

A
  • macrophages
  • dendritic cells
  • natural killer cells
  • mast cells
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13
Q

What are the features of macrophages?

A

develop from monocytes, large pale pink cytoplasm, kidney bean nucleus

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14
Q

What do dendritic cells do?

A

present in large numbers in tissues, APCs

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15
Q

What do natural killer cells do?

A

granular, kill infected cells and cancer cells, kill antibody bound cells and pathogens

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16
Q

What do mast cells look like and do?

A

fried egg appliance, granular, protect mucosal surfaces

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17
Q

What are PAMPs?

A

pathogen associated molecular pattern which are on the surface of pathogens

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18
Q

What are PRRs?

A

pattern recognition receptors that are on the surface of cells and intracellular to bind to and detect PAMPs

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19
Q

What is phagocytosis facilitated by?

A

opsonisation so macrophages can engulf pathogens

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20
Q

What are the main steps of phagocytosis?

A
  • macrophages express PRRs
  • PRRs bind to PAMPs
  • phagocytic cup engulfs target to form phagosome
  • fusion with lysosomes to form phagolysosome
  • debris released into extracellular fluid
  • pathogen-derived peptides expressed on MHC-II
  • pro-inflammatory mediators released eg TNFalpha
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21
Q

What is opsonisation?

A

coating of pathogens by opsonins to enhance phagocytosis

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22
Q

What do virally-produced interferons activate?

A

immune cells
signals nearby infected cells to undergo apoptosis
signals nearby uninfected cells to decrease protein synthesis and destroy RNA

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23
Q

What cells to natural killers target?

A

cells with less MHC-I so virally infected and cancer cells

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24
Q

What happens when mast cells degranulate?

A
  • release pro-inflammatory mediators

- increased acute inflammation

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25
Q

What is macrophage activation enhanced by?

A

IFNgamma (made by NKC)

increased MHC-II expression

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26
Q

What is neutrophil trans-endothelial migration?

A

gets neutrophils to the tissues through the blood and is triggered by pro-inflammatory mediators

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27
Q

How does this process of transendothelial migration occur?

A
  • margination
  • binding to adhesion molecules on endothelial cells
  • migration across endothelial by diapedesis
  • movement by chemotaxis
  • activation by PAMPs and TNFalpha
28
Q

What are the three ways that neutrophils can kill?

A
  • Phagocytosis: either phagolysosomal killing or ROS-dependent (reactive oxygen species)
  • Degranulation: digestive enzymes which stop replication
  • Neutrophil extracellular traps: release of intracellular structures which traps pathogens so macrophages can engulf them
29
Q

What do macrophages release?

A

anti-inflammatory particles and stimulate wound healing

30
Q

What does CRP do?

A

primes the bacteria for destruction by complement and is used as an inflammation marker

31
Q

Where do the components of complement come from?

A
  • MBL and C3 are another part of the acute phase response

- complement is made in the liber and enters inflamed tissues and there is a cascade reaction

32
Q

What are the component proteins that leak out and what is this triggered by?

A
  • kinins, coagulation factors and fibrinolytic leak out

- release is triggered by pro-inflammatory cytokines and histamine that increase permeability

33
Q

What does C3 split into and what do these cause?

A
  • C3a and C3b

- these cause pathogen killing, opsonisation, leukocyte recruitment and removal of immune complexes

34
Q

What causes the splitting of C3?

A

mannose-binding lectin or C3b (human have inhibitory proteins so this doesn’t happen)

35
Q

What does C3b then cause?

A

more reactions so C5b made which is the membrane attack complex

36
Q

What does the MAC do?

A

causes cell to burst when placed in the membrane

37
Q

What do C3a and C5a cause?

A
  • acute inflammation
  • activate mast cells
  • act on vessels
38
Q

What does C3b do?

A

acts as an opsonin and causes C5 to split

39
Q

What are the two types of T cells?

A

CD4+ T are regulators

CD8+ T are killers

40
Q

How to T and B cells enter lymph nodes?

A

transendothelial migration from high endothelial venules

41
Q

How do B cells recognise antigens?

A

using membrane-bound antibodies on their surface

42
Q

What happens when the B and T cells enter the lymph nodes?

A
  • B cells to lymphoid follicle
  • T cells to T cell area to interact with dendritic cells
  • all leave through medullary sinus and efferent vessels
43
Q

What are the types of B cells?

A
  • plasma cells: secrete soluble, antigen-specific antibodies

- memory cells: circulate around the body

44
Q

What happens when an antigen enters a lymph node?

A
  • chemokine attract B cells

- B cells need antigen and helper signals from T cell to be activated

45
Q

What is the first antibody to be secreted?

A

IgM

46
Q

What do antibodies do?

A
  • recognise

- effect so clear with heavy chain region with complement and Fc receptors

47
Q

What does IgM do?

A
  • B cell activation when on B cell
  • first in adaptive response
  • agglutination and complement system activation
48
Q

What do IgG and IgM activate?

A

complement cascade with Fc region

49
Q

What does IgG do?

A
  • agglutination
  • complement activation
  • foetal immune protection (dimeric)
  • neutralisation (monomeric)
  • opsonisation
  • natural killer activation
  • transported across placenta
50
Q

What do IgG and secretory IgA act to do?

A

neutralise so prevent pathogens from infecting host cells

51
Q

What do IgG opsonins on pathogen bind to?

A

Fcgamma receptor on neutrophil and enhance phagocytosis

52
Q

What is ADCC?

A

Antibody-Dependent Cell-mediated Cytotoxicity

- activation of natural killer cells by the Fc region of IgG

53
Q

What are the two types of IgG and their roles?

A
  • monomeric helps with neutralisation
  • dimeric helps with neonatal defence and neutralisation
  • transported in breast milk to protect neonatal GI tract lining
54
Q

What is IgD?

A

B cell receptor for B cell activation

55
Q

What does IgE do?

A

allergic response eg allergy, asthma and anaphylaxis

56
Q

What is the specific state that antigens must be in for T cells to recognise them?

A

antigens must be presented to the T cells’ TCR by MHC molecules

57
Q

What do Class I MHC do?

A

are expressed on all nucleated cells and present peptide antigens to CD8+ T cells

58
Q

What do Class II MHC do?

A

expressed only on APCs so dendritic cells and macrophages, B cells
present peptide antigen to CD4+ T cells

59
Q

What are the steps of inflammation involving dendritic cells?

A
  • debris from phagocyte released
  • dendritic cells phagocytise pathogen-derived particles
  • TNFalpha stimulates tissue-resident dendritic cells to increase expression of stimulants
  • dendritic cells digest proteins and display peptides with MHCs
60
Q

What do dendritic cells express?

A

both MHC I and II so both CD4+ and CD8+ can bind

61
Q

What do Th0 cells do?

A

IL2 initiates Th0 to be cloned to make more IL2 so CD8+ cells differentiate into killer cells in the T zone

62
Q

What do Th1 cells do?

A
  • migrate to inflamed tissue to help macrophages

- make IFN gamma to enhance killing by stimulating reactive oxygen species production

63
Q

What do Tfh cells do?

A
  • form germinal centres

- help B cells survive

64
Q

What do CD8+ T cells differentiate into?

A

cytotoxic T cell s which release perforin and granzymes to make cell undergo apoptosis

65
Q

How is tissue repair stimulated?

A
  • less histamine is produced

- macrophages release anti-inflammatory markers

My Principles (13 decks)

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