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PH2113 Disease & Drugs 1 > U3 L1 Immunology Recap > Flashcards

U3 L1 Immunology Recap Flashcards

1
Q

What is the innate humoral response?

A

Complement

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2
Q

What cells are involved in the innate cellular response?

A

NK cells, macrophages, monocytes, neutrophils, mast cells

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3
Q

What is the adaptive humoral response?

A

Antibody involvement

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4
Q

What is the adaptive cellular response?

A

Involvement of B cells and T cells

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5
Q

What are the 1st, 2nd and 3rd lines of defence?

A

1st - physical and chemical barriers
2nd - innate
3rd - adaptive

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6
Q

What are the characteristics of innate response?

A
  • Rapid
  • Same response with repeated exposure
  • Exists at birth
  • Non-specific and indiscriminate
  • No immune memory
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7
Q

What are the characteristics of adaptive response?

A
  • Specific to epitope or antigen
  • Immune memory
  • Distinguishes between self and non-self
  • Relies on mechanisms that develop as result of infection (slow)
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8
Q

What are the functions of a macrophage?

A
  1. Secretion of enzymes, cytokines to modulate immune response
  2. Phagocytosis
  3. Antigen processing and presentation to T helper cells via MHC Class II
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9
Q

What are the types of macrophage?

A
  1. Alveolar - in lungs, phagocytosis
  2. Kuppfer - in liver, initiate immune response
  3. Microglia - in brain, immune surveillance and phagocytosis
  4. Splenic - in spleen, elimination of old/damaged RBC
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10
Q

What is the process of phagocytosis?

A
  1. Chemotaxis
  2. Adherence of microbe to macrophage
  3. Ingestion of microbe
  4. Phagosome formation
  5. Formation of phagolysosome
  6. Digestion by enzymes
  7. Formation of residual body
  8. Discharge of waste materials
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11
Q

What is chemotaxis?

A

Movement of phagocyte towards site of infection e.g. due to release of factors by bacteria

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12
Q

How do microorganisms adhere to a phagocytic cell surface?

A

Adherence to receptors eg.
- lectin receptors
- complement (C3b) receptors
- Fc receptors

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13
Q

How is the microorganism injested by the phagocytosing cell?

A
  • adherence to receptors causes cytokine-skeletal activation of phagocyte
  • activation of actin-myosin contractile network to extend pseudopodia around microorganism
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14
Q

What is the pH of a phagosome?

A

PH 7

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15
Q

What sort of pH is present in a phagolysosome?

A

Acidic

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16
Q

Why is pH in a phagolysosome low?

A

Stimulate activity of agents e.g. reactive oxygen species, proteases, lysozymes to break down the microorganism

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17
Q

What is the function of reactive oxygen species, hydrogen peroxide, hydroxyl radicals in a phagolysosome?

A

Oxidise microbial membranes causing destruction

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18
Q

What is the function of lysozyme?

A

Destruction of bacterial membranes

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19
Q

What cells are considered granulocytes?

A
  1. Neutrophils
  2. Eosinophils
  3. Basophils
  4. Mast cells
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20
Q

What are neutrophils involved in?

A
  1. Acute inflammation
  2. Phagocytosis
  3. Killing of bacteria by oxidative mechanisms
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21
Q

What kinds of factors do neutrophils release?

A

Kinins, chemotactic factors (e.g. IL-8), pyrogens, bacteriostatic proteins

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22
Q

What is the most abundant leukocyte?

A

Neutrophil

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23
Q

What are eosinophils involved in?

A
  1. Allergic reactions
  2. Parasite immunity (not phagocytosed)
  3. Some inflammatory conditions
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24
Q

What is respiratory burst?

What cells undergo respiratory burst?

A

Generation of reactive oxygen species

Macrophages, neutrophils, eosinophils

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25
Q

What chemotactic factors attract eosinophils towards the site of infection?

What receptors do eosinophils have?

A

IL-5, C3a

Fc and C3b receptors

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26
Q

How are basophils and mast cells linked?

A

Basophils travel from blood into tissue where they become mast cells

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27
Q

What kinds of antibodies do mast cells bind on their surface?

A

IgE via Fc receptors

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28
Q

What causes degranulation of mast cells?

A

Binding of antigen (Ag) to IgE; causes IgE cross links in membrane

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29
Q

What preformed molecules do mast cell granules contain?

A
  • histamine
  • proteases
  • chemotactic factors for neutrophils, eosinophils
  • pro-inflammatory cytokines
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30
Q

What is a lymphocyte?

A

White blood cell

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31
Q

What is the function of a natural killer cell?

A

To destroy tumour cells or host cells infected with a virus

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32
Q

How do NK cells recognise tumour or virally infected cells?

A

Tumour or virally infected cells have modified glycoproteins o surface which NK cell recognises

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33
Q

What follows the activation of NK cells after interaction with modified glycoproteins?

A

Extracellular granule release containing:
- perforin (membrane permeabilising protein)
- TNF
- proteases

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34
Q

What are the three functions of the complement system?

A
  1. Opsonisation of microorganisms for phagocytosis
  2. Activation of leukocytes in immune defence
  3. Lysis of target cells via MAC
35
Q

How is the adaptive response specific?

A
  • antibodies and B cells
  • T cell receptors and T cells
36
Q

How are B cells activated?

A
  1. Naive B cell internalises antigen bound to BCR
  2. antigen fragments presented on MHC class II on B cell surface
  3. Th cells recognise antigens
  4. T cell-B cell interaction; CD40 binds to CD40 (ligands), Th secrete cytokines
37
Q

What are antigens?

A

Proteins, polypeptides released from damaged cells (e.g. virally infected) or

Resident proteins on foreign cell surface

38
Q

What is a B cell epitope or antigenic determinant?

A

Specific linear peptide sequence or pattern of amino acid residues recognised by given antibody

39
Q

What is a conformational epitope?

A

Folding of polypeptide brings amino acids together and forms epitope

40
Q

What is a linear epitope?

A

Series of adjacent amino acids in chain recognisable by antigen

41
Q

Why is a protein considered increasingly immunogenic with size?

A

More epitopes on surface

42
Q

What are haptens?

A

Low molecular molecules that bind covalently to proteins which will elicit an immune response

(Antibodies can respond to haptens)

43
Q

What is IgG?

A

Monomer - classic antibody structure, binds to Fc receptors

Placental transfer

Fixes complement

Involved in opsonisation; enables NK cells to undergo ADCC

44
Q

What determines antibody class?

A

Fc domain

45
Q

What is ADCC?

A

Antibody Directed Cell Cytotoxicity

46
Q

What is IgM?

A

Pentameter - 5 monomers linked

First Ig made by foetus and B cells

B cell antibodies are IgM

Fixes complement

47
Q

What is IgA?

A

Dimer

Major secretory Ig e.g. mucosal surfaces, tears

Binds to Fc receptors on some cells

48
Q

What is IgE?

A

Monomer, least common serum Ig

Binds to basophils, mast cells in tissues, eosinophils

Important in allergic rxns

49
Q

What is selective activation of B lymphocytes?

A

Each B cell has specific IgM, bind to specific antigen

50
Q

What is clonal proliferation of B lymphocytes?

A

Multiplication of activated B cell clones

51
Q

What occurs after clonal proliferation of B cells?

A

Some differentiation into plasma cells

Some activated B cells will enter lymphoid tissue, become memory cells

52
Q

What is the function of a plasma cell?

A

Production and secretion of monoclonal antibodies (mainly IgM) to initiate immune response

Can produce IgG, IgM, IgE, IgA with same epitope if T cells involved

53
Q

What is the function of memory cells?

A

Respond to same initial antigen upon re-exposure

54
Q

How do B cells meet antigens?

A
  1. Antigen delivered to lymphoid tissue, spleen, nodes
  2. B cells circulate from lymphoid tissue in blood and lymph
  3. Mutations in memory cells can increase affinity for target antigens
55
Q

What are some effector functions of antibodies?

A
  1. B cell membrane IgM as antigen receptor
  2. Plasma cell antibodies neutralise antigens
  3. IgG, IgM activate classical complement
  4. IgG - opsonisation of foreign surfaces
  5. ADCC targeted by IgG
  6. IgE triggers mast cell activation
  7. IgA mediates mucosal immunity
  8. IgG mediates neonatal immunity
56
Q

What are cytokines?

A

Chemical signals transmitting effector functions in immune response

57
Q

What are CSFs?

What are the main functions of CSFs?

A

Cytokines - Colony-Stimulating Factors

Activate and cause proliferation of granulocytes, monocytes

58
Q

What cells release CSFs?

A

T-cells, macrophages, fibroblasts, mast cells, endothelial cells

59
Q

What are TNFs?

A

Tumour Necrosis Factors - pro-inflammatory

60
Q

What cells release TNF-alpha?

What is TNF-alpha involved in?

A

T cells, macrophages

Tumour cytotoxicity, phagocytosis activation

61
Q

What cells release TNF-beta?

What is TNF-beta involved in?

A

T cells

Antiviral activity, activation of phagocytosis

62
Q

What are IFNs?

What cells release IFNalpha?

What cells release IFNbeta?

A

Interferons

Mostly macrophages

Fibroblasts

63
Q

What are the functions of IFNalpha and IFNbeta?

A

Antiviral
Increases expression of MHC I

64
Q

What cells secrete INFgamma?

What are the functions of IFNgamma?

A

T cells

Antiviral, macrophage activation, enhanced MHC I and MHC II
Maturation of Cytotoxic T cells

65
Q

What are interleukins?

A

Chemicals secreted by one leukocyte to act on another

66
Q

What is the function of IL-1?

What cells secrete IL-1?

A

Pro-inflammatory
- proliferation of activated B and T cells
- induction of fever
- induction of IL-6

Macrophages, fibroblasts

67
Q

How do T cells mediate specific cellular immune responses?

A

Each T cell has TCR of single specificity; recognises only specific T cell epitope

68
Q

What follows T cell activation via TCR interaction with specific Ag?

A

clonal selection and proliferation of T cells

formation of T cell effector and memory cells specific for original Ag

69
Q

T cells will only respond to an antigen that is presented on the surface of host cells in association with

A

proteins derived from Major Histocompatibility Complex (MHC)

70
Q

MHC also known as

A

HLA - human leukocyte antigen

71
Q

What is the function of MHCs?

A

act as ‘identity markers’ on surface of host cells with which T cells interact

72
Q

What cells present MHC I?

To which cells do these cells present the MHC I with antigenic peptide?

A

all nucleated cells

cytotoxic T cells (CD8+)

73
Q

MHC I presents a peptide epitope derived from where?

A
  1. intracellular synthesis
  2. processing of proteins e.g. foreign viral
74
Q

What is the effector function of cytotoxic T cells, CD8+?

A

to kill ‘altered’ host cells

75
Q

What cells express MHC II on their surface?

For which is MHC II expressed?

A

antigen presenting cells - macrophages, dendritic cells, B cells

T helper cells, CD4+

76
Q

Where is the peptide epitope presented by MHC II derived from?

A

endocytosis of extracellular proteins which is then processed to generate peptide epitopes

77
Q

What is the effector function of a T helper cell, CD4+?

What do T helper cells upregulate in response to immune stimuli?

A

to promote humoral and cell mediated response
- promote antibody response to antigens
- promote killing of infected cells by CD8+ and macrophages

MHC II expression

78
Q

Diversity of MHCs is responsible for

A
  • organ rejection after transplantation
  • some hypersensitivity reactions
79
Q

What are the subtypes of MHC I?

What are the subtypes of MHC II?

Are all subtypes of the MHCs found on cells carrying MHC I or MHC II?

A

MHC I A, MHC I B, MHC I C

MHC II DP, MHC II DQ, MHC II DR

Yes

80
Q

There is polymorphic diversity in the subtypes of MHC I A, B, C and MHC II …. what does this mean?

A

different genentic versions of the same subtype, therefore diversity of binding sites and how they are recognised

81
Q

How many polymorphic forms of MHC II DP will an individual inherit?

A

one from each parent therefore will have two polymorphic forms (most likely)

82
Q

In total how many subtypes of MHC does each individual express from each parent?

What is the benefit to expressing various subtypes?

A

6

provides broader repertoire for peptide presentation by individual, therefore recognition of foreign antigens

83
Q

What is the benefit to the polymorphic diversity of each MHC I and II subtype?

A

limits the damage that a viral mutation could have on population, wider protection

PH2113 Disease & Drugs 1 (5 decks)

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