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RUSVM Principles Of Infectious Diseases > Week 6 + 7 > Flashcards

Week 6 + 7 Flashcards

1
Q

Define immune system, immune response, and immunology

A
  • immune system: collection of cells, tissues, and molecules that mediate resistance to foreign elements (antigens)
  • immune response: coordinated reaction of these cells and molecules to antigens
  • immunology: stud of the immune system, including its responses to microbial pathogens and damaged tissues, and its role in disease
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2
Q

Define antigen and epitope/antigenic determinant

A
  • antigen: “antibody generator”, molecules that induce an immune response when introduced to the body
  • epitope (antigenic determinant): part of an antigen that is actually responsible for inducing the immune response and binding to the products of the immune response (lymphocyte receptors + antibodies)
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3
Q

If the immune system is unable to discriminate between foreign elements an components of its own system, what is the result?

A
  • autoimmunity
  • immune responses should only be generated when components of the immune system come into contact with non-self elements
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4
Q

What are the two types of immune defense?

A
  • innate immunity (NON-SPECIFIC): physical barriers, inflammation, complement
  • adaptive immunity (SPECIFIC): humoral immunity, cellular immunity
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5
Q

What are features of innate and adaptive immunity?

A
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6
Q

T/F: there are not many physical or chemical aspects of the immune system

A
  • false
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7
Q

What are PAMPs?

A
  • pathogen-associated molecular patterns
  • components that are shared between different types of pathogens and present a molecular composition that differs from “self”
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8
Q

What are DAMPs?

A
  • damage-associated molecular patterns
  • released when cells die (intracellular DAMPs) or generated when connective tissue is damaged (extracellular DAMPs)
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9
Q

What are pattern recognition receptors (PRRs)?

A
  • receptors of innate immunity that recognize PAMPs and DAMPs
  • soluble or membrane bound
  • signalling of phagocytic
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10
Q

T/F: the immune system consists of just white blood cells

A
  • false
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11
Q

What are some features of neutrophils?

A
  • appearance: segmented nucleus, granular cytoplsam
  • location in health: blood
  • lifespan in health: 48-74 hrs
  • primary function: antimicrobial effectors, primarily in acute bacteria infection
  • mechanism of action: phagocytosis, degranulation, neutrophil extracellular trap formation
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12
Q

What are some features of eosinophils?

A
  • appearance: characteristic eosinophilic granules
  • location in health: blood no tissue lining gastrointestinal tract and airways
  • lifespan in health: days to weeks
  • primary function: antiparasitic effectors, particularly in helminths infection, some antiviral action, roles in allergy
  • mechanism of action: degranulation, limited phagocytosis
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13
Q

What are some features of basophils?

A
  • appearance: characteristic blue-purple basophilic granules
  • location in health: blood
  • lifespan in health: days
  • primary function: mediator of inflammation
  • mechanism of action: degranulation
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14
Q

What are some features of mast cells?

A
  • appearance: round nucleus, cytoplasm densely packed with purple granules
  • location in health: tissue,particularly connective tissue surrounding vasculature +nerves,and lamina propria of the mucosa
  • lifespan in health: weeks to months
  • primary function: immune surveillance, mediator and amplifier of inflammation and allergy
  • mechanism of action: detection of threats ad release of inflammatory mediators via degranulation (vasoactive amines) or synthesis of lipid mediators and cytokines
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15
Q

What are some features of macrophages?

A
  • appearance: round nucleus, clear-vacuolated cytoplasm, irregular cell shape
  • location in health: peripheral tissue
  • lifespan in health: months
  • primary function: immune surveillance, moderate antimicrobial capacity, limited antigen presentation
  • mechanism of action: detection of threats and release of inflammatory mediators, phagocytosis
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16
Q

What are some features of dendritic cells?

A
  • appearance: round nucleus, clear cytoplasm, irregular shape w/ long branched projections (dendrites)
  • location in health: tissues
  • lifespan in health: months
  • primary function: immune surveillance, antigen processing and presentation
  • mechanism of action:detection of threats and release of inflammatory mediators, endocytosis and phagocytosis
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17
Q

What are some features of natural killer (NK) cells?

A
  • appearance: large lymphoid cell, round nucleus, azurophilic cytoplasmic granules
  • location in health: blood, spleen
  • lifespan in health: months
  • primary function: destruction of virally infected or abnormal host cells (including tumor cells)
  • mechanism of action: recognition of virally infected or abnormal host cells and targeted release of cytotoxic granules
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18
Q

What are some features of lymphocytes?

A
  • appearance: round nucleus, clear cytoplasm, high N:C ratio
  • location in health: blood, tissues, secondary lymphoid organs
  • lifespan in health: weeks to months, years (memory cells)
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19
Q

The two major types of lymphocytes are:

A
  • T cells + B cells
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20
Q

What are some differences between T cells and B cells?

A
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21
Q

What is the complement system?

A
  • collection of plasma proteins that are individually inert but can interact in a cascade once they are activated
  • attacks the cellular membrane leading to cell death
    -act as signalling molecules that. Recruit immune cells to inflammatory sites
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22
Q

What molecules communicate via cell-to-cell contact in the immune system?

A
  • receptors: expressed on the surface of a cell Orin intracellular compartments
  • ligands: molecules that activate receptors, soluble or membrane bound
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23
Q

What are cytokines? Some features?

A
  • proteins with diverse functions such as cell growth, activation
  • interleukins: communication between cells
  • chemokines chemotaxis
24
Q

What are the sentinel cells of the immune system?

A
25
Q

What activates sentinel cells? What does this cause?

A
  • exposed to PAMPs, DAMPs, or pro-inflammatory cytokines
  • cell activation
    • upregulation of cellular antimicrobial defenses
    • release of pro-inflammatory chemokines, lipid mediators, an cytokines
26
Q

What role do mast cells play in inflammation?

A
  • vasocative molecules
    • histamine
    • serotonine
  • vasodilation
  • raise vascular permeability
  • more leukocytes
  • easier to migrate to tissue
27
Q

What are systemic consequences of inflammation?

A
28
Q

Describe leukocyte extravasation

A
  • macrophages and dendritic cells produce cytokines such as that activate the endothelial cells to express selections and ligands for integrins and to secrete chemokines
  • selectins: rolling
  • integrins: adhesion
  • chemokines: migration
29
Q

What is leukocyte chemotaxis?

A
30
Q

Describe leukocyte kinetics during inflammation

A
  • lymphocytes are present once the adaptive immune system is engaged in the response
  • monocytes/macrophages predominate at later stages of inflammation
  • neutrophils predominate acute inflammation
31
Q

What is phagocytosis?

A
  • an active process of capturing and ingesting foreign objects/microorganisms by phagocytes
    • neutrophils and macrophages
  • destruction of microorganisms, damaged cells and cellular debris, foreign objects
  • induction of cytokine production
  • processing and presentation of antigens
32
Q

What are functions of phagocytosis?

A
  • recognition of microbe
  • endocytosis
  • phagosome maturation
  • fusion of phagosome and lysosome
  • killing of bacteria inside the phagolysosome
33
Q

What are intracellular killing mechanisms? Some features?

A
  • oxidative pathway
    • use of oxygen and glucose increases several fold “respiratory burst”
    • reactive oxygen species (ROS)
    • reactive nitrogen species (RNS)
    • toxic to microorganisms
  • non-oxidative pathway
    • dependent on the action of the toxic substances present in lysosomes
    • cationic proteins: damage bacterial cell wall
    • lysozyme: damages the mucopeptides in the bacterial cell wall
    • lactoferrin: sequestration iron inhibiting bacterial growth
    • proteolytic + hydrologic enzymes: digest killed bacteria
34
Q

What is the purpose of Neutrophil Extracellular Traps (NETs)?

A
  • raise inflammatory stimulus
  • extrude strands of nuclear DNA and associated proteins into the extracellular fluid
  • traps and kills microbes
35
Q

What is the function of Neutrophil Extracellular Traps (NETs)?

A
  • raise inflammatory stimulus
  • extrude strands of nuclear DNA and associated proteins into the extracellular fluid trapping and killing microbes
36
Q

What are features of the complement system?

A
  • collection of circulating and membrane-associate proteins
  • many movement proteins are proteolytic enzymes
  • activation occurs in a sequential manner
  • 3 activation pathways
  • alternative
  • classical
  • lectin
37
Q

What are the three pathways of the complement system and some features?

A
  • alternative pathway: complement proteins are activated on microbial surfaces (because complement regulatory proteins are not present on microbes, only host cells)
  • lectin pathway: activated when a carbohydrate-binding plasma protein, mannose-binding lectin protein (MBL), binds to terminal mannose receptors on the surface glycoproteins
  • classical pathway: activated by antibodies that bind to microbes or other antigens
38
Q

What are features of the membrane attack complex (MAC)?

A
  • breaches the cell membrane of the microbe, allowing water to rush into the cell
  • destruction by osmotic lysis
39
Q

What are features of type I interferons?

A
  • produced by virus-infected cells
  • non-specific response to viral infection
  • IFN-alpha + IFN-beta
    • inhibit viral replication
    • induce a antiviral state
40
Q

What is the function of natural killer cells?

A
  • recognize and respond to infected and stressed cells
    • killing of cells
    • secretion of IFN-gamma (stimulates and activates macrophages)
41
Q

How do natural killer cells perform their function?

A
42
Q

What are molecules tasked with antigen processing and presentation?

A
  • Major histocompatibility complex (MHC) molecules
    • class I + II
  • T cells only recognize antigens presented on a MHC molecule
43
Q

What does MHC I present antigens to?

A
  • CD8+ T cells
44
Q

What does MHC II present antigens to?

A
  • CD4+ T-cells
45
Q

What activates a naive T-cell?

A
  • dendritic cell
46
Q

How do dendritic cells activate naive t-cells?

A
  • immature DC’s encounter antigens in tissues
  • migration to lymphoid tissue and maturation
  • antigen presentation by mature DC’s in lymph nodes
47
Q

What are the different types of activated T-cells?

A
  • t-cell subsets
    • CD4+
      • Th1, Th2, Th17
      • express surface molecules and secrete cytokines that activate other cells
    • CD8+
      • cytotoxic T lymphocytes (CTLs)
      • killing of infected cells
48
Q

What is the cellular response of CD4+ TH1 cells?

A
  • cytokine secretion
  • activation of macrophages
  • activation of CTLs (CD8+)
49
Q

What is the cellular response of CD8+ CTLs?

A
  • induces apoptosis of infected cells
50
Q

T/F; antigen recognition of B cells is restricted by MHC presentation

A
  • false; not restricted
51
Q

What are the kinds of humoral responses of B cells?

A
  • activated by Th cells
  • T-independent activation
52
Q

What are the classes/isotypes of immunoglobulins (antibodies)?

A
  • IgG
  • IgM
  • IgA
  • IgE
  • IgD
53
Q

What are differences in Ig isotypes?

A
54
Q

What are functions of different Ig isotypes?

A
55
Q

What is the distribution of different Ig isotypes?

A
  • IgM: blood
  • IgG: blood + tissues
  • IgA: mucous membranes
  • IgE: epithelial tissue
56
Q

T/F: IgM is the major antibody of secondary responses

A
  • False: IgG (memory cells)
57
Q

What is the general pathway of immune response?

A

RUSVM Principles Of Infectious Diseases (6 decks)

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