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OPHTH Immunology > Introduction to Immunology > Flashcards

Introduction to Immunology Flashcards

1
Q

What are 3 types of cells involved in innate immunity?

A
  1. neutrophils
  2. macrophages
  3. Natural Killer (NK) cells
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2
Q

What are 3 types of soluble factors involved in innate immunity?

A
  1. Acute-phase proteins
  2. Cytokines
  3. Complement
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3
Q

What are 5 cell types involved in acquired immunity?

A
  1. T lymphocytes
  2. B lymphocytes
  3. dendritic cells
  4. eosinophils
  5. basophils/mast cells
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4
Q

What is 1 type of soluble factor involved in acquired immunity?

A

antibodies

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5
Q

What is the acute inflammatory response?

A

innate response to tissue damage

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6
Q

What are 5 features of the acute-phase inflammatory response?

A
  1. Rise in body temperature (fever)
  2. Production of proteins (acute phase proteins) mainly by liver (CRP, SAP, MBL)
  3. CRP + SAP bind to molecules on cell wall of bacteria + fungi - pattern recognition
  4. MBL binds to mannose sugar molecules not often found on mammalian cells
  5. molecules are non-specific but direct phagocytes to identify + ingest infectious agent
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7
Q

What are the 3 key types of acute phase proteins, mainly produced by the liver, during the acute phase response?

A
  1. CRP
  2. Serum amyloid protein
  3. Mannan-binding lectin
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8
Q

What are cytokines?

A
  • small proteins, carry messages between cells e.g. stimulate activation, killing, secretion, proliferation.
  • kick-start acquired immune response
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9
Q

What 3 things can the cells of the innate immune system be divided into (remember: comprise of neutrophils, macrophages, NK cells)?

A
  • Granluar leukocytes:
    1. NK cells
    2. Macrophages
    3. Granulocytes (neutrophils, eosinophils, basophils)
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10
Q

What is the structure of neutrophils?

A

Polymorphonuclear (PMN) neutrophils - multi-lobed nucleus

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11
Q

What proportion of the circulating WBCs is formed by neutrophils?

A

50-70%

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12
Q

What is the broad function of neutrophils?

A

phagocytic

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13
Q

What is the structure of eosinophils?

A

bi-lobed nucleus

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14
Q

What proportion of the circulating WBC are eosinophils?

A

1-3%

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15
Q

What is the role of eosinophils in innate immunity?

A

immune response to parasites, helminths and allergic responses

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16
Q

What proportino of WBC are basophils?

A

<1%

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17
Q

What are 2 functions of basophils in innate immunity?

A
  1. not phagocytic - release granules containing histamines, serotonin, prostaglandins
  2. important in Th2 responses - kickstarting acquired immune response
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18
Q

What is the function of NK cells?

A

identify + kill virus-infected + tumour cells, complex recognition system - recognise HLA molecule of virus infected cell or tumour + kill them

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19
Q

What is the structure of macrophages?

A

mononuclear phagocytes

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20
Q

What are the 2 main functions of macrophages?

A
  1. garbage disposal
  2. present foreign cells to immune system
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21
Q

What are antigens?

A

glycoprotein molecules which react with antibodies or T cells; not all can induce immune response - those that can are termed immunogens

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22
Q

What is the structure of the most basic antibody?

A

bivalent - 2 binding sites

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23
Q

What proportion of serum Ig is formed by each Ig type?

A
  • IgG: 75%
  • IgM: 10%
  • IgA: 15%
  • IgE: <1%
  • IgD: <1%
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24
Q

What are 2 important characteristics of IgG?

A
  • crosses the placenta - protection of newborns
  • long serum half-life
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25
Q

What is the structure of IgG?

A

bivalent - 2 identical antigen binding sites

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26
Q

What is the structure of IgM?

A

complex of 5 linked bivalent monomeric antibodies - 10 identical binding sites (multivalent), star-like shape

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27
Q

Which immune responses are IgG and IgM involved in respectively?

A

IgG - secondary, IgM - primary immune response

28
Q

What is the structure of IgA and where is it found?

A

2 basic monomers - dimer with secretory piece, found in body secretions e.g. mucus membranes in GI tract

29
Q

Why is the secretory component of IgA important?

A

protects it from digestive enzymes

30
Q

How does IgE works?

A

binds to basophils + mast cells, triggers release of histamines

31
Q

What is an epitope?

A

particular antibody recognises an antigen because that antibody’s inding site is complementary to the EPITOPE, a region approx. 6 amino acids long, on the antigen (forms basis of specificty of antigen recognition)

32
Q

What are 4 mechanisms via which an antibody can kill a virus?

A
  1. binding to virus + preventing attachment to the cell
  2. opsonisation: virus-antibody complex recognised + phagocytosed by macrophage
  3. comlement-mediated lysis of enveloped viruses: cascade of enzymes in the blood which leads to destruction of cell membranes + destruction of viral envelope
  4. antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by NK-like cells
32
Q

What are 4 mechanisms via which an antibody can kill a virus?

A
  1. binding to virus + preventing attachment to the cell
  2. opsonisation: virus-antibody complex recognised + phagocytosed by macrophage
  3. comlement-mediated lysis of enveloped viruses: cascade of enzymes in the blood which leads to destruction of cell membranes + destruction of viral envelope
  4. antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by NK-like cells
32
Q

What are 4 mechanisms via which an antibody can kill a virus?

A
  1. binding to virus + preventing attachment to the cell
  2. opsonisation: virus-antibody complex recognised + phagocytosed by macrophage
  3. comlement-mediated lysis of enveloped viruses: cascade of enzymes in the blood which leads to destruction of cell membranes + destruction of viral envelope
  4. antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by NK-like cells
33
Q

What are lymphocytes?

A

agranular leuckocytes, 20-40% of circulating WBC

34
Q

What are lymphocytes?

A

agranular leuckocytes, 20-40% of circulating WBC

35
Q

What are 2 types of lymphocytes?

A
  1. T (thymus-derived) cells
  2. B (bone marrow-derived) cells
  3. NK (natural killer) cells
36
Q

What are T cells divided into (2 types)?

A
  1. Helper T cells: recognise antigen, help B cells make antibodies and T cells to kill
  2. Cytotoxic T cells: poisonous to cells, kill cells infected by viruses and intracellular bacteria
37
Q

What is the overall role of B cells?

A

make antibodies, have insoluble antigen-binding receptor on its surface; have multiple clones of this receptor -> monoclonal antibodies

38
Q

Where are lymphocyte precursors producted?

A

haematopoietic tissue in the bone marrow

39
Q

What proportion of T cells are destroyed in the thymus during thymal education and why?

A

95-99% - have the potential to recognise host cells

40
Q

What is the B cell antigen receptor?

A

membrane-bound antibody - surface Ig

40
Q

What is the B cell antigen receptor?

A

membrane-bound antibody - surface Ig

41
Q

What is the T cell antigen receptor?

A

2 protein chains (alpha and beta) - together form TCR, binds to digested antigen fragments

42
Q

What is recognised by the T-cell antigen receptor (TCR)?

A

complex of antigen peptide and HLA (MHC) molecule - HLA binds to little fragments of the pathogen + transports them to the cell surface to be recognised

43
Q

What generates clonal diversity in a) B cells and b) T cells?

A

random genetic recombinations within each cell among multiple copies of a) Ig genes and b) TCR genes, undergo random splicing and recombination leading to large repertoire of anigen receptors

44
Q

What proportion of naive T cells is a typical antigen recognised by?

A

1 in 10^5

45
Q

What does clonal selection involve?

A
  • antigen binds to surface receptor on B cell (Ig) or the TCR, causes seletive expansion of that clone
  • the receptors which bind with highest affinity to the antigen are selected for, outcompete the other receptors proliferate + survive to form effector lymphocytes
45
Q

What does clonal selection involve?

A
  • antigen binds to surface receptor on B cell (Ig) or the TCR, causes seletive expansion of that clone
  • the receptors which bind with highest affinity to the antigen are selected for, outcompete the other receptors proliferate + survive to form effector lymphocytes
46
Q

What are 2 possible outcomes for lymphocytes that have proliferated recently?

A
  1. most: die after fulfilling function
  2. some: survive as memory cells, epigenetically modified so frequency of receptors increase next time host infected
46
Q

What are 2 possible outcomes for lymphocytes that have proliferated recently?

A
  1. most: die after fulfilling function
  2. some: survive as memory cells, epigenetically modified so frequency of receptors increase next time host infected
47
Q

What type of infected cells are killed by cytotoxic T lymphocytes?

A

cells infected by viruses or intracellular bacteria

48
Q

How do CTL kill virus/intracellular bacteria infected cells?

A

recognises antigen peptide + HLA complex, releases granules of enzymes including proteases which digest DNA - APOPTOSIS

49
Q

How does a T cell meet its antigen?

A

antigens are taken up by specialised APCs, transported from the tissues into secondary lymphoid organs (lymph nodes, spleen + MALT), where they meet T cells + initiate the acquired immune response

50
Q

What are the 3 types of APCs?

A
  1. B lymphocytes
  2. Macrographes
  3. Dendritic cells (most efficient)
51
Q

What are primary lymphoid organs + the 2 types?

A

produce lymphocytes - bone marrow + thymus

52
Q

What are 3 types of secondary lymphoid organs?

A
  1. lymph nodes
  2. spleen
  3. mucosa-associated lymphoid tissue (MALT)
53
Q

What proportion of the day do T cells spend in the blood vs the lymph?

A

1-2 hours in the blood, rest of ay in lymph

54
Q

Where are antigens present in the blood taken to?

A

spleen

55
Q

Does the innate immune response generate memory?

A

no

55
Q

Does the innate immune response generate memory?

A

no

56
Q

What happens to adaptive immune responses on repeated exposure to the potential pathogen?

A

adaptive responses can increase in magnitude

57
Q

What is primary vs secondary response?

A

primary= response made by naive lymphocytes when they first encounter their specific antigen. secondary= response made by memory lymphocytes when they re-encounter the specific antigen

58
Q

What are the 3 types of surface markers on T cells?

A

CD3, CD4, CD8

59
Q

What are the surface markers associated with B cells?

A

CD19, CD20, surface immunoglobulin class II MHC

OPHTH Immunology (8 decks)

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