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Immunology > Test 3- L11 > Flashcards

Test 3- L11 Flashcards

1
Q

What kind of immunity is important for helping with extracellular pathogens

A

Humoral immunity- mediated by antibodies, complement proteins

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2
Q

What is important for helping with intracellular pathogens

A

Cellular immunity

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3
Q

What are the possible outcomes of infection

A

Protective immunity, partial incomplete or temporary protection, no immunity (tetanus), death, development of a deleterious host immune response

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4
Q

What are the 2 types of immunity you can get from the pathogen

A

Sterilizing immunity- completely removing pathogen from the body
Non-sterilizing immunity- herpes virus (not entirely eliminated- comes back with stress)

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5
Q

Outcomes of infection- (1)Host survives with partial, incomplete, or temporary immunity & (2)Host survival with no immunity examples

A

1- Influenza- subsequent exposure to the same pathogen is less severe
2- Tetanus- Immune response to subsequent exposure to same pathogen are identical to the first

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6
Q

Outcomes of infection- (1) death, (2) development of a deleterious host immune response, (3) alteration of the immune response, (4) autoimmune response examples

A

1- HIV
2- Scarring TB- damage to normal tissue
3- EBV makes viral IL-10 to encourage a Th2 response instead of Th1 resulting in increased infection
4-Klebsiella -> ankylosing spondylitis
Campylobacter jejuni -> Guillain Barre syndrome

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7
Q

What cells help in combating intracellular pathogens

A

NK cells- identify lack of self that some viral infections produce via downregulation of HLA-1

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8
Q

Time course of infection

A
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9
Q

2 common extracellular pathogens

A

Strep, Staph

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10
Q

2 types of intracellular pathogens and their types

A

Obligate intracellular- Chlamydia, Rickettsia
Facultative intracellular- Salmonella, Mycobacteria

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11
Q

Humoral immunity combats

A

Extracellular pathogens

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12
Q

Cell-mediated immunity combats

A

Intracellular pathogens

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13
Q

Examples of humoral immunity & extracellular pathogens

A

Antibodies, antibody/phagocytosis, compliment, lysozyme

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14
Q

Examples of cell-mediated immunity & cells to kill intracellular pathogens

A

TH1 cells (IFN gamma), CD8+ T cells (killvia peptide presentation), NK cells, anti-viral state (generated by cytokines)

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15
Q

Once a pathogen is inside a host cell it is protected against what & what is used to identify and kill it

A

The actions of complement and antibodies, cellular immune mechanisms are needed to recognize that the cell is infected
and eliminate it

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16
Q

The 5 primary means of defense against extracellular bacteria
are:

A

1- Opsonizing antibody and phagocytosis
2-Neutralizing antibody
3-Complement (classical, MBL, and alternative pathways)
4- ADCC (antibody-dependent cell cytotoxicity
5-IgA production

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17
Q

Opsonizing antibody and phagocytosis is important for mediating attack by

A

Encapsulated bacteria- opsonizing antibody directed against
the capsule. When deposited along with complement C3b on the surface of an extracellular pathogen, uptake by phagocytes is greatly enhanced.

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18
Q

Clinical examples of the
importance of phagocytosis in host defense are:

A

Macrophages in the reticuloendothelial system
engulfing bacteria in the blood (sepsis), neutropenic patients

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19
Q

Neutropenic patients are highly susceptible to infections with

A

Extracellular pathogens

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20
Q

Neutralizing antibody does what

A

Inhibits attachment to receptors on host tissue

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21
Q

Complement (classical, MBL, and alternative pathways) is good for what

A

Bacterial cell lysis and opsonization

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22
Q

ADCC is good for what

A

Many different types of pathogenic bacteria

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23
Q

IgA production does what

A

Major means that the host uses to defend against extracellular pathogen infections at mucosal surfaces

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24
Q

Many extracellular bacteria avoid the harsh environment of the circulatory system and/or
within tissues by doing what

A

Adhering to, colonizing, and infecting only mucosal surfaces where the amount of phagocytic cells and complement are very low

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25
Q

Many extracellular bacteria avoid the harsh environment of the circulatory system and/or
within tissues- examples are:

A

Bacteria that cause cholera, pertussis, and diphtheria

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26
Q

Bacteria that cause cholera, pertussis, and diphtheria- what are important for combating these pathogens

A

Mucosal immunity (IgA)- neutralizes toxins

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27
Q

What are the 2 types of toxins produced by bacteria

A

Endotoxins, exotoxins

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28
Q

Endotoxins (LPS/LOS) are produced by

A

Gram negative bacteria- cannot be made by a toxoid

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29
Q

LPS is an exogenous pyrogen that induces sequential production of what endogenous pyrogens

A

IL-1, TNF-α, and IL-6, and thus, causes fever

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30
Q

LPS mediates what kind of shock & comes from what

A

Septic/ endotoxic shock via IL-1, TNF-α, and IL-6 induced cytokine storm (makes too much of them)

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31
Q

Endotoxin (LPS/LOS) activates what pathway

A

Alternate complement pathway

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32
Q

Endotoxin (LPS/LOS) biological activity

A

BROAD biological activity

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33
Q

Endotoxin (LPS/LOS) doesn’t induce neutralizing antibody but may induce:

A

Polyclonal B cell stimulation

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34
Q

Endotoxin (LPS/LOS) cannot be made into what

A

A toxoid

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35
Q

What is a toxoid

A

Inactive form of a toxin we can create vaccines by using

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36
Q

Exotoxins are produced by

A

Either gram negative bacteria or gram-positive (most often) bacteria

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37
Q

Only certain exotoxins called _______ directly induce cytokine release through activation of T cells

A

Superantigens- release large quantities of proinflammatory cytokines via too many T cells (TOXIC SHOCK)

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38
Q

Exotoxin biological activity

A

Specific pharmacological activity depending upon the toxin- specific T cells get targeted

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39
Q

Exotoxins are generally active at what levels

A

Levels that are not immunogenic

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40
Q

Many Exotoxins can be converted into what

A

Toxoids

41
Q

Exotoxins- disease doesn’t necessarily lead to what

A

Protective immunity- so we use toxoids for immunizations

42
Q

What are virulence factors

A

Substances produced by a pathogenic organism that enables it to cause disease

43
Q

Virulence factors are ______ and are targets for ______

A

Capsules/ toxins, vaccine development

44
Q

What are examples of current vaccines that target the immune response against virulence factors

A

Diphtheria (toxin), tetanus (toxin), pertussis (toxin), flu type B (capsule) and strep. pneuomoniae (capsule)

45
Q

Immunity to intracellular bacteria is primarily mediated by

A

T lymphocytes

46
Q

What are the primary T lymphocytes that mediate immunity to intracellular bacteria

A

CD4+ T helper-1 lymphocytes

47
Q

What do CD4+ T helper-1 lymphocytes produce

A

IFN-γ and other phagocyte-activating factors are of primary importance in resolving infections with obligate intracellular bacteria

48
Q

Which of the following molecules is most important for
immunity from an infection with an encapsulated bacterium
(Strep.).
1. IFNα
2. IgG
3. IgE
4. HLA class I
5. IL-12

A
  1. IFNα-viral (phagocytosis)
    **2. IgG- can opsonize- important for getting ahold of encapsulated bacteria
  2. IgE- Helminth
  3. HLA class I- Intracellular
  4. IL-12- Th1 response
49
Q

Superantigens stimulate an immune response that is
composed of
1. A polyclonal antibody response
2. A monoclonal antibody response
3. A polyclonal T cell response
4. A monoclonal T cell response

A
  1. A polyclonal T cell response
    Polyclonal/monoclonal: how many T cell or B cell clones are being activated
50
Q

Examples of facultative vs. obligate intracellular bacteria

A

Facultative (mycobacterium)- can live outside or inside cells
Obligate (Chlamydia)- must be in cells to be pathogenic

51
Q

What is critical for combating intracellular pathogens

A

Activation of CD4+ Th1 and production of IFNγ

52
Q

What are the 2 categories of interferons & what do they include

A

Type 1: IFN-α and IFN-β
Type 2: IFN-γ

53
Q

IFN-α and IFN-β are considered what

A

Non-immune interferons (fibroblast interferons)

54
Q

IFN-α and IFN-β are produced by what cells

A

Almost all nucleated cells of the body upon infection with a virus
or other stimulus

55
Q

IFN-γ is produced by what cells

A

T-lymphocytes and NK cells

56
Q

Type 2 (IFN-γ) encourages what type of response

A

Phagocytosis & Th1 response

57
Q

5 type 1 and type 2 interferon anti-bacterial (IFNα/β/γ) effects on non- macrophage cells

A

1-Restriction of protein synthesis
2-Decrease membrane fluidity
3-Induces iNOS and O2-
4-Altered metabolism
5-Increased HLA class I –leads to increased CTL activity

58
Q

Activated macrophages express what

A

HLA1 & HLA2

59
Q

Th1 cells secrete_____ to stimulate macrophages to kill ______ pathogens

A

IFNγ, intracellular

60
Q

Synergistic effects of host and pathogen factors to
activate macrophages

A
61
Q

Activated macrophages are
characterized by several things to include, but not limited to: (Type 2 interferon IFNγ only)

A

-Increased cytoplasmic volume
-Increased respiratory burst
-Increased HLA class I and II expression (enhanced antigen presentation)
-Increased C3b and Fc receptors on surface of macrophage
-Increased metabolism
-Induces iNOS and O2-

62
Q

Cytotoxic cells in intracellular bacterial infections- early in response

A

NK and γ/delta TCR+ T lymphocytes (innate)

63
Q

Cytotoxic cells in intracellular bacterial infections- later in response

A

-CD4+ Th1 activation (IFN-γ and IL-2)
-CD8+ CTLs recognize processed antigen
-Each of above may produce significant IFN-γ quantities

64
Q

What are 2 cytolytic cells (breakdown target cell)

A

NK cells and CD8+ T cells

65
Q

What responses are critical for eradicating intracellular bacteria (Chlamydia)

A

Th1 mediated responses

66
Q

Cytotoxic T lymphocytes have been shown to do what

A

Recognize certain cytosolic
bacterial antigens with HLA class I to kill infected cell

67
Q

Many obligate intracellular pathogens drive the immune response towards a _____ type of response

A

Th2 (antibody producing)

68
Q

Why do obligate intracellular pathogens encourage Th2 responses

A

To down-regulate the Th1 responses

69
Q

Th1 responses are good at killing what pathogens

A

Intracellular pathogens

70
Q

Another mechanism used by intracellular pathogens to evade the immune response is to become _______ within the host cell – in effect, “hiding” intracellularly until the immune response wanes and it is safe for them to renew active growth

A

Latent

71
Q

Strong CD4+ Th1 cell responses correlate with protective immunity against what

A

Fungi

72
Q

During intracellular bacterial infections ____ are important
early on, while ____ are important later in the response.
1. CD8+ T cells –CD4+ T cell
2. NK cells –CD8+ T cells
3. NK cells –γdelta T cells
4. γdelta T cells –NK cells

A
  1. NK cells –CD8+ T cells
73
Q

What immune responses are good at killing fungi

A

Innate & adaptive

74
Q

What does the innate immune responses include

A

Neutrophil phagocytosis (PRR recognize fungal PAMPS), complement (MBL pathway)

75
Q

What does the adaptive immune responses include

A

-Th1-mediated responses important for controlling opportunistic fungal infections
-IFN-γ is necessary for increasing phagocytic activity
-Th17 are also involved in controlling fungi

76
Q

What are the phases of virally infected cells

A

Extracellular & intracellular

77
Q

Viruses are considered

A

Obligate intracellular pathogens

78
Q

Viruses are processed _____ and ________

A

Endogenously (HLA class 1), exogenously (HLA class 2) on APCs

79
Q

Where else can viral antigens be found

A

Unprocessed in the host cell membrane

80
Q

Humoral immunity to viral infections- 4 responses of antibodies

A

-Antibody can neutralize viral attachment
-Opsonization of virus or host cells expressing viral antigens in their surface (enhance phagocytosis by neutrophils & macrophages)
-Activating complement to destroy enveloped viral particles via classical pathway
-ADCC of infected host cells

81
Q

Antibodies can help only when the virus is

A

Outside the host cell

82
Q

Cellular immunity against intracellular virus particles: Early (innate)

A

NK cells sense lack of self via lack of self

83
Q

Cellular immunity against intracellular virus particles: late (adaptive phase)

A

CTL (Cytotoxic t cell specific for HLA class 1), induction of antiviral state by interferons (IFNα/β by all nucleated cells) or IFNγ (Th1, CTL, γdelta TCR+ cells, NK cells)

84
Q

Do interferons directly kill viruses

A

NO

85
Q

What are the functions of interferons on viral infections

A

-Decrease in membrane fluidity, preventing viral penetration and release from the host cell
-Production of enzymes which destroy viral nucleic acids
-Inhibition of viral protein synthesis
-Upregulation of HLA expression on the host cell surface
-KNOWN AS ANTIVIRAL STATE

86
Q

What is the viral response to our defense

A

Block IFN (hepatitis), block HLA (herpes, adenoviruses), block complement activation (influenza A), antigenic variation (rapid mutations- influenza), production of homologues of immune regulatory cytokines (IL-10 produced by EBV)

87
Q

Innate- cellular response

A

NK cells- kills virus infected host cells, produces type 2 interferons
Infected host cell- Produces type 1 interferons that induce antiviral state

88
Q

Adaptive- humoral response

A

IgG, IgM, IgA antibodies- blocks virus binding to host cell receptors
IgG, IgM antibodies- Enhances phagocytosis of virus particles (IgG) and activates complement pathway (IgG/ IgM)

89
Q

Adaptive- cellular response

A

IFNγ secreted by CD4+ Th1 (type 2 interferons)- induces antiviral state in host cells
CD8+ CTLs- Kill virus-infected host cells
Killer cells/ antibody- ADCC

90
Q

Immunity to protozoan parasites (unicellular organisms):

A

Extracellular protozoan parasites:
Ab (Th2 dominant responses)
Intracellular protozoan parasites:
CMI (Th1 dominant responses)

91
Q

Immune Responses to Helminthic Parasites

A

*IgE antibody responses (Th2 dominant responses)
*Eosinophils

92
Q

Septic syndrome and SIRS –
mediated by ______

A

Massive release of proinflammatory cytokines

93
Q

A hallmark of helminthic parasite infections in humans is the production of _____

A

IgE

94
Q

Another hallmark of helminth infections is ____

A

Eosinophilia (abnormally high
level of eosinophils in the circulation) which interact with IgE to produce the
allergy symptoms.

95
Q

Large amount of what 4 things can cause septic syndrome & SIRS

A

-LPS- gram negative bacteria (engage PAMPS)
-Peptidoglycan, teichoic acid- gram positive bacteria (engage PAMPS)
-F-met-leu-phe 5’- mCPG DNA (engage PAMPS)
-Viral or bacterial superantigens

96
Q

Your patient is found to have a deficiency in IFN-γ production.
Infections with which of the following agents are most like to be exacerbated in this patient?
A. Parasitic helminths
B. Encapsulated bacteria
C. Viruses and other intracellular pathogens
D. Toxin elaborating bacteria

A

C. Viruses and other intracellular pathogens

97
Q

Type 1 interferons exert their antiviral effects by which
of the following mechanisms?
A. Increasing membrane fluidity
B. Increasing endogenous antigen processing pathways
C. Increasing viral protein synthesis to increase presentation

A

B. Increasing endogenous antigen processing pathways

98
Q

The host response to parasitic helminth infestations is
most similar to which of the following?
A. Allergies and allergic asthma
B. Sepsis or the systemic inflammatory response syndrome (SIRS)
C. Type 1 hereditary angioedema
D. Toxic shock syndrome
E. Responses to viral infections

A

A. Allergies and allergic asthma

Immunology (3 decks)

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