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Principles - Kate > Immunology > Flashcards

Immunology Flashcards

1
Q

what does the immune system do in brief?

A

identifies and eliminates microorganisms and other harmful substances

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2
Q

what two things do you need for a balanced immune system?

A

protection from pathogens and rejection of donor tissue = optimal effectiveness

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3
Q

what is an immune over-reaction?

A

reaction to self (autoimmunity) or reaction to innocuous substances (allergies)

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4
Q

what is and immune under-reaction?

A

recurrent infections and cancer

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5
Q

what are some soluble factors? (natural

A

cytokines, acute phase proteins, inflammatory mediators, complement proteins

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6
Q

what are some immune cells? (natural)

A

macrophages, mast cells, natural killer cells, neutrophils

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7
Q

what are some soluble factors? (adaptive)

A

cytokines and antibodies

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8
Q

what are some immune cells? (adaptive)

A

B cells and T cells

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9
Q

what are the two types of immunity?

A

innate (natural) immunity and acquired (adaptive) immunity

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10
Q

what are the points of entry for a pathogen?

A

digestive system, respiratory system, urogenital system, skin damage

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11
Q

what are the two routes of attack for a pathogen?

A

circulatory system and lymphatic system

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12
Q

how does the constitutive barrier skin to infection work?

A

physical barrier (constantly undergo renewal and replacement), physiological factors (low pH and low oxygen tension), sebaceous glands (secrete hydrophobic hols, lysozyme, ammonia, antimicrobial peptides)

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13
Q

how does that constitutive barriers mucous to infection work?

A

secreted mucous, lines all body cavities that come into contact with the environment (respiratory, gastrointestinal, urogenital), mucous traps bacteria which is then removed by ciliated cells

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14
Q

how does the constitutive barrier commensal bacteria to infection work?

A

symbiotic relationship with host, reside at epithelial surfaces

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15
Q

what often happens to the bodies bacteria when antibiotics are used?

A

eradication of the normal flora, resulting in opportunistic infection, organisms rapidly colonise as undefended ecological niche

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16
Q

what is innate immunity?

A

present continuously, present from birth. same generic response occurs to many different microbial species, rapid response

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17
Q

what is acquired immunity?

A

induced by the presence of foreign materials, a unique response is generated to each individual pathogen, slow response

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18
Q

what are two types of phagocytes? (eating cells)

A

macrophages and dendritic cells

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19
Q

why are pathogens detected by the immune system?

A

pathogens express signature molecules not found in human cells known as ‘pathogen associated molecular patterns’ (PAMPS)

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20
Q

what do innate immune cells express in response to PAMPS?

A

partner receptors known as ‘pattern-recognition receptor (PRRs)

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21
Q

what phagocyte ingests extracellular bacteria and fungi?

A

macrophages

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22
Q

what are the modes of ingestion for a macrophage?

A

pinocytosis (fluid of surrounding cells) receptor-mediated endocytosis (molecules bound to membrane receptors is internalised) - important step for adaptive immunity, phagocytosis (intact particles are internalised whole)

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23
Q

what is opsonisation?

A

its the coating of pathogens by soluble factors (opsonins) to enhance phagocytosis

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24
Q

what are some examples of opsonins?

A

C3b, C-reactive protein (CRP), IgG/IgM

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25
Q

when do mast cells step in?

A

when the parasite is too large to be phagocytosed

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26
Q

what happens when mast cells degranulate?

A

release of pre-formed pro inflammatory substances (e.g. histamine)

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27
Q

what does inflammation promote?

A

vascular changes, recruitment and activation of neutrophils (trans endothelial migration), bacteria produce chemicals that attract neutrophils

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28
Q

what activates neutrophils?

A

PAMPs and TNF alpha

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29
Q

what do neutrophils bind to on the endothelial cells ?

A

adhesion molecules (selection ICAM-1)

30
Q

how do neutrophils migrate across the endothelium?

A

via diapedesis

31
Q

how do neutrophils move within the tissue?

A

via chemotaxis

32
Q

what do neutrophils do? (phagocytosis)

A

use PPRs to bind to and phagocytose pathogens. kill internalised pathogens via phagolysosomal killing or ROS-dependent killing

33
Q

what do neutrophils do? (degranulation)

A

release of anti-bacterial proteins from neutrophil granules directly into extracellular milieu (direct killing of extracellular pathogens bacteria and fungi)

34
Q

what do neutrophils do? (NETs)

A

trap and kill pathogens in an extracellular environment, colour of puss is due to neutrophils.

35
Q

what happens during an acute phase response?

A

changes in the plasma concentration of specific proteins in response to inflammation, driven by pro-inflammatory mediators released by activated macrophages. mediated by liver hepatocytes which produce a variety of acute phase proteins (CRP and complement system proteins)

36
Q

what does the C-reactive protein do?

A

a major acute phase protein in humans, used as a marker for inflammation

37
Q

what do virally infected cells produce and release?

A

cytokines called interferons (IFN alpha/beta)

38
Q

what cells can recognise and destroy virally infected cells?

A

natural-killer cells

39
Q

what does the complement system create when activated?

A

a cascade of chemical reactions the promotes: opsonisation, direct pathogen killing, acute inflammation and leukocyte recruitment

40
Q

what does C3 breakdown to?

A

C3a and C3b

41
Q

what do B cells do?

A

responsible for humoral immune responses, produce antibodies that attack pathogens circulating in the blood and lymph, key role in defence against extracellular pathogens

42
Q

what do T cells do?

A

responsible for cellular immune responses, key role in defence against intracellular pathogens: CD4+ T cells (key regulators of the entire immune system), CD8+ T cells (kill virally infected body cells)

43
Q

what are antibodies?

A

proteins that bind to one specific antigen, each has. a unique variable region that binds to one specific. antigen. complex of four polypeptide chains (2x light 2x heavy chains)

44
Q

what two forms are antibodies expressed in?

A

membrane bound and soluble

45
Q

what is the B cell receptor (BCR)?

A

an antibody

46
Q

what do T cells recognise?

A

peptide antigens

47
Q

what are MHC molecules?

A

major histocompatibility complex (MHC) molecules also referred to as human leucocyte antigens, display peptide antigens to T cells, able to present many different peptides to T cells

48
Q

what are the two major classes of MHC molecules?

A

Class I MHC: expressed on all nucleated cells and present peptide antigens to CD8+ T cells
Class II MHC: expressed only on professional antigen presenting cells (APCs) (dendritic cells, macrophages and B cells) present peptide antigen to CD4+ T cells

49
Q

where to antigen-specific T and B cells develop?

A

lymphatic tissue (bone marrow and thymus)

50
Q

what do mature inactive antigen-specific T and B cells do?

A

circulate between the different blood, secondary lymphoid tissues (tonsils and lymph-nodes) and lymphatic vessels

51
Q

how do antigens enter the lymph node?

A

via afferent lymphatics

52
Q

what do dendritic cells do?

A

phagocytose pathogen - derives particles and antigens, pro-inflammatory TNF alpha stimulates immature tissue-resident dendritic cells to increase expression of co-stimulatory molecule. they digest indigested proteins and display small peptides derived from these on their cell surface in complex with MHC

53
Q

what signals do B cells need to receive to become fully activated and clonal proliferate in response to protein antigens?

A

antigen and helping signals

54
Q

what is the first antibody made against an infecting pathogen during a humeral immune response?

A

IgM in its secreted pentameric form

55
Q

what does IgM serve as? (membrane bound monomeric form)

A

B cell antigen receptor - mediated B cell activation

56
Q

where is IgM present?

A

in plasma and secretory fluid (agglutination and complement system activation)

57
Q

what is agglutination?

A

(immune complex formation) the action of an antibody when it cross-links multiple antigens producing clumps of antigens, increasing efficacy of pathogen elimination by enhancing phagocytosis, prevents viruses from binding to infecting host cells

58
Q

what is IgG?

A

the most abundant antibody in normal human serum, dominant Ig type produced during a secondary (memory) immune response

59
Q

what are the functions of IgG?

A

agglutination, complement system activation, foetal immune protection, neutralisation, opsonisation, natural killer cell activation

60
Q

how doe IgG provide foetal immune protection?

A

IgG antibodies are transported across the placenta, directly into the foetal blood circulation

61
Q

what is neutralisation mediated by?

A

specific antigen binding to high affinity IgG and secretory IgA antibodies

62
Q

what is a good activator for natural killer cells?

A

IgG

63
Q

what does IgA do?

A

present in serum in monomeric form, function is neutralisation, present in secretory fluids in dimeric form, functions in neonatal defence and neutralisation at mucosal sites

64
Q

how does IgA provide neonatal protection?

A

IgA antibodies are transported into colostrum and breast milk in order to protect the GI tract of neonates

65
Q

what do IgE antibodies do?

A

trigger allergic responses e.g. asthma and anaphylaxis

66
Q

what do antigen-activated CD8+ T cells proliferate and differentiate into?

A

killer cells: cytotoxic T lymphocytes (CTLs or Tc cells) migrate out of the lymph node and enter sites of infection in order to kill infected host cells

67
Q

what growth factor promotes the proliferation and differentiation of CD4+ T cells and CD8+ T cells?

A

IL-2

68
Q

what does the effector TH1 T cell help macrophages become?

A

super-killers

69
Q

what is apoptosis?

A

a form of cell death that does not affect inflammation, cell suicide

70
Q

what are macrophages good at stimulating?

A

wound and tissue repair, can switch between pro inflammatory and anti inflammatory

Principles - Kate (10 decks)

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