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BMS150 - Biomedicine > Week 2 - Immunology + Micro > Flashcards

Week 2 - Immunology + Micro Flashcards

1
Q

What organs make up the upper respiratory system?

A

Nasal cavity
Nostril
Oral cavity
Pharynx

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2
Q

What organs make up the lower respiratory system?

A

Larynx
Trachea
Bronchus (left and right)
Lungs
Diaphragm

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3
Q

What are the main functions of the conducting zone?

A

Filters, warms and moistens the air going into our body and conducts it to the respiratory zone

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4
Q

What is the main function of the respiratory zone?

A

Gas exchange

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5
Q

The lower respiratory system is free of _____, while the upper respiratory system (nose, nasal cavity and pharynx) has a diverse ____

A

resident microbiota
microbiome

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6
Q

Haemophilus spp. is a gram negative anaerobe that is grown on ____ agar and requires ____ and ____ to survive

A

Chocolate
X Factor (Hemin)
V Factor (NAD+)

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7
Q

_____ is the major cause of sepsis and meningitis

A

H. influenzae

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8
Q

Veillonella spp. is a gram-negative anaerobe that can break down lactate to produce ____ and break down nitrate into ____

A

ATP
nitric oxide

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9
Q

Staphylococcus spp. is a gram-positive facultative anaerobe that is responsible for:

A

pneumonia
meningitis
osteomyelitis
toxic shock syndrome
sepsis
scalded skin syndrome
folliculitis
pimples

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10
Q

Diphtheroids are gram-positive aerobes that live in hair follicles, ferment ____, lower skin ____ and can cause ____

A

carbohydrates
pH
pimples

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11
Q

Alpha-hemolytic streptococci are gram-positive facultative anaerobes grown on ____ agar and are ____ pathogens

A

blood
opportunistic

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12
Q

What are some signs and symptoms of strep throat (streptococcal pharyngitis)?

A
  • pain during swallowing
  • bad breath
  • fever
  • malaise
  • headache
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13
Q

Strep throat is caused by streptococcus ___ , which are gram-positive, beta-hemolytic, facultative anaerobes

A

pyogenes

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14
Q

What are the virulence factors of streptococcus pyogenes?

A

M protein (C3b inhibitor)
- Disrupts opsonization and lysis of foreign materials
Hyaluronic acid capsule
- camouflage system surrounding cell and allowing it to be undetected by phagocytes
Streptokinases
- what S. pyogenes use to break down clots
C5a peptidase
- chemotaxis (attracts WBC’s to site of infection)
Pyrogenic (erythrogenic) toxins
- releases cytokines
Streptolysin O
- lyses all human blood cells

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15
Q

Scarlet fever (strawberry tongue and skin rash) and rheumatic fever (fever, painful joints, involuntary movements) can both result from ____

A

streptococcal pharyngitis

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16
Q

How is streptococcal pharyngitis treated?

A

penicillins (G or V) or amoxicillin

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17
Q

A less common bacterial pharyngitis is caused by ____, which presents as a sore throat, localized pain, fever, oozing of fluid and fluid thickening into pseudomembrane

A

diphtheria

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18
Q

Corynebacterium diptheria is a pleiomorphic ____ bacteria and is ubiquitous (found on skin, respiratory etc.)

A

gram-positive

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19
Q

What is the virulence factor of diphtheria and how does it work?

A

diphtheria toxin (AB toxin)
1) B subunit of diphtheria toxin attaches to receptor
2) endocytosis is triggered
3) Subunit A is released
4) Subunit A destroys elongation factor, preventing mRNA transcription in the nucleus of the human cell

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20
Q

How is diphtheria transmitted?

A

from P2P via respiratory droplets/skin contact

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21
Q

How is diphtheria treated?

A

antitoxin, erythromycin, vaccination (DTaP vaccine)

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22
Q

What is the process by which rhinoviruses cause the common cold?

A

1) ICAM-1 (intracellular adhesion molecule-1) binds to receptor on rhinovirus
2) endocytosis is triggered
3) transcription and translation of virus

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23
Q

Binding between ICAM-1 and rhinovirus is optimal as 33 degrees and binds better as the virus is restricted to the ____ tract

A

upper respiratory

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24
Q

What helps viruses attach to host cell receptors?

A

spike proteins

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25
Q

Endosomes have a low pH and protective toll receptors that bind to viral proteins being translated triggering an _____ cascade and _____

A

antiviral
inflammatory mediators

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26
Q

True or false: Production of new viruses kill nasal epithelial cells and infected cells lose ciliary action and slough off when dead

A

True

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27
Q

True or False: Death of cells releases inflammatory chemicals and stimulates nerve cells

A

True

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28
Q

Severity relates to serotypes. What are the types of serotypes?

A

HRV-B: less severe and less frequent
HRV-A/C: more severe, effects vary from country-to-country

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29
Q

How do HRV infections increase susceptibility to bacteria?

A

1 - makes host more prone to infection by secondary bacteria
2 - promotes staph into pneumocytes (increased release of IL-6 and IL-8)
3 - Virus more likely to be internalized
4 - HRV stimulates S. pneumonia allowing for adhesion to tracheal epithelial cells by inducing surface expression of PAFR
5 - Macrophages activation

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30
Q

What is the pathogenesis of adenoviruses?

A

1) attachment and entry (endocytosis): binds to CAR (coxsackie B/adenovirus) membrane receptors
2) receptors expressed in many/most tissues
3) virus inhibits DNA/mRNA/protein synthesis
4) host cell lysis

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31
Q

Most coronaviruses belong to the ____ and ____ variants

A

alpha
beta

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32
Q

____ and ___ coronavirus variants mostly affect bird species

A

delta
gamma

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33
Q

What is the structure of coronavirus?

A
  • spike glycoproteins
  • nucleoprotein and RNA genome
  • membrane protein
  • envelope small membrane protein pentamer
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34
Q

What is the pathogenesis of coronavirus?

A

1) cleavage of SARS-CoV2 S protein
2) activation of S2 domain
3) fusion of viral and host membranes

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35
Q

What is the causative agent of mononucleosis?

A

human herpesvirus 4 (Epstein-Barr virus) - enveloped, dsDNA, icosahedral capsid

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36
Q

Mononucleosis infects ____, can become latent and prevents apoptosis in these cells

A

B lymphocytes

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37
Q

Symptoms of mononucleosis include:

A

sore throat, fever, enlarged lymph nodes, and extreme fatigue

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38
Q

What are the infection stages of epstein-barr virus?

A

1 - virus gets out into blood
2 - enters B cells and becomes lysogenic
3 - incorporated into host cell DNA (circulates in body for rest of life)
4 - virus is shed out into mucus and out of body through mucus tract
5 - trigger of immune response

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39
Q

What diseases are associated with EBV?

A
  • oral hairy leukoplakia
  • burkitt’s lymphoma
  • chronic fatigue syndrome
  • nasopharyngeal cancer
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40
Q

True or false: EBV is ubiquitous in humans and thus prevention is impossible

A

True

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41
Q

Antigens must be presented to a ___ in order for them to recognize them

A

T-cell

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42
Q

Antigens are presented by being bound to particular ___ found on other cells, known as ___ in mice and rats or ____ in humans

A

proteins
MHC (major histocompatibility) proteins
HLA (human leukocyte antigen) proteins

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43
Q

The ___ protein can help a T-cell distinguish between foreign and self antigen

A

HLA

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44
Q

True or false: Antigens are not bound tightly to HLA proteins

A

True

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45
Q

HLA proteins can present a wide variety of antigens to a wide variety of ____

A

lymphocytes

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46
Q

HLA class I proteins interact with _____ and binds ____ antigens, while HLA class II proteins interacts with _____ and binds ____ antigens

A

cytotoxic T-cells
intracellular
T-helper cells
extracellular

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47
Q

What is the co-receptor for HLA class I and II?

A

CD8
CD4

48
Q

Alpha 1, 2 and 3 subunits form the ____ heavy chain in the HLA-I structure

A

glycoprotein

49
Q

The antigen binding site for MHC class I is found between the ___ and ___ subunits, and binds antigens 8-10 amino acids long

A

alpha 1
alpha 2

50
Q

The CD8 co-receptor on the cytotoxic T cells binds to the ___ subunit in MHC class I

A

alpha 3

51
Q

The ___ microglobulin subunit is not covalently bound to the heavy chain and is needed for proper folding

A

beta 2

52
Q

The HLA-II structure is composed of two ____ of similar sizes which are ____ and ____

A

glycoproteins
beta 1- beta 2
alpha 1 - alpha 2

53
Q

The antigen binding site for MHC class II is found between the ___ and ___ subunits, and binds antigens 13-18 amino acids long

A

beta 1
alpha 1

54
Q

The CD4 co-receptor on the T-helper cells binds to the ___ and ___ subunit

A

beta 2
alpha 2

55
Q

HLA type I molecules subtypes are indicated by the designation:

A

A, B or C

56
Q

HLA type II molecules subtypes are all indicated by the designation:

A

D

57
Q

True or False: Differing allelic variants of class I and II HLA proteins is the main reason we usually reject organs from randomly-matched organ donors

A

true

58
Q

True or false: The presence of particular allelic variants have been associated with increased risk of some autoimmune diseases

A

true

59
Q

HLA-1 types are expressed on almost all _____, with the highest expression level found on ____

A

nucleated cells
lymphocytes

60
Q

HLA-1 proteins typically bind intracellular antigens via the ____ pathway, and most of the time these are _____

A

endogenous
self-antigens

61
Q

True or false: During viral infection, some HLA-1 molecules on a cell will express viral peptides, while some will express host peptides

A

true

62
Q

What is the endogenous pathway of HLA-I expression?

A

1) source of antigenic peptide is from the cytosol
2) peptide is derived from proteasomal degradation of foreign/altered proteins
3) peptide is transported into the RER and loaded onto the HLA-1 protein
4) HLA-1 is expressed on the cell surface

63
Q

Proteins destined for degradation by proteosomes get tagged via a process known as ____

A

ubiquitylation

64
Q

Cells that are very good at presenting HLA-1 bound peptides to T-cells have specialized proteosomes called _____

A

immunoproteosomes

65
Q

Immunoproteosomes have slightly different subunits that are substituted into the regular proteosome and this can be induced by _____

A

cytokines (IFN-gamma and TNF-alpha)

66
Q

The peptides that are produced by immunoproteosomes bind with better affinity to ____

A

HLA-1

67
Q

The protein that translates the peptide fragment into the RER for loading onto the HLA-1 is called:

A

TAP

67
Q

Some viruses have the ability to block ____, preventing their viral peptides from being expressed on HLA-1

A

TAP

68
Q

The presence of intracellular invaders will trigger an increase in transcription of _____, which occurs via binding to NOD-like receptors

A

HLA-1 proteins

69
Q

Binding of NOD-like receptors ____ the expression of HLA-1, and NODs activate ___

A

upregulate
NFkB

70
Q

What are the steps of the NFkB pathway?

A

1) Upon activation of the pathway, an inhibitory protein (IkB) is phosphorylated and degraded
2) NFkB is free to travel to the nucleus
3) Promotion of transcription of NFkB target gene

71
Q

Which cytokines increase the expression of HLA-1 molecules?

A
  • Both type 1 and type 2 interferons (IFN)
  • Tumor necrosis factor alpha (TNF-alpha)
71
Q

The source of the type 1 and 2 interferons and TNF-alpha results from:

A

he activation or infection (or both) of a cell nearby

72
Q

Local antigen-presenting cells are the first to produce ____ and ____, and later activated T-helper cells will contribute to ____ production

A

TNF-alpha
type-1 interferons
IFN-gamma

73
Q

Once a peptide-bound HLA-1 is expressed on the surface of a cell, it can bind a ______ and activate it, which will kill infected cells by inducing apoptosis

A

CD8 cytotoxic T-cell

74
Q

HLA-2 types are expressed exclusively on ____

A

antigen-presenting cells
- professional: dendritic cells, macrophages, B-cells
- non-professional: fibroblasts (skin), glial cells, pancreatic beta cells, thymic epithelial cells, intraepithelial lymphocytes, vascular endothelial cells

75
Q

Dendritic cells always express high levels of ___ and are very good at co-stimulating _____

A

HLA-2
helper T-cells

76
Q

Macrophages need to be activated before they express ___, and are good at co-stimulating ___

A

HLA-2
helper T-cells

77
Q

B-cells always express ____ at low levels and are good at co-stimulating ____

A

HLA-2
helper T-cells

78
Q

Non-professional APCs will only express ____ under particular conditions such as sustained ____

A

HLA-2
inflammation

78
Q

HLA-2 proteins bind extracellular antigens via the _____ pathway

A

exogenous

79
Q

In B-cells, IFN-gamma ____ HLA-2, however IL-4 ___ HLA-2

A

downregulates
upregulates

80
Q

HLA-2 expression is upregulated by the _____ cytokine

A

interferon-gamma

81
Q

What are the steps involved in HLA-2 expression via the exogenous pathway?

A

1) Phagocytosis is upregulated and is the source of the peptides that are loaded on HLA-2 (can occur through regular pathway or antibody mediated in B-cells)
2) The phagocytosed antigen is processed in a phagosome and merges with a vesicle containing the HLA-2
3) The antigen is loaded onto HLA-2 and expressed on the surface of the cell

82
Q

How can phagocytosis by B-cells be antibody-mediated?

A

1 - antigen binds to specific antibody on the surface of the B-cell
2 - antigen and antibody are phagocytosed together (receptor-mediated endocytosis)
3 - antibody is recycled back to the surface of the cell and antigen is processed in an endosome

83
Q

How do we ensure a cytosolic antigen isn’t loaded onto a HLA-2 in the RER?

A
  • In the RER, the HLA-2 protein associates with the invariant chain which prevents this
  • blocks the HLA-2 from being accessible to the intracellular antigen so has nowhere else to go except HLA-1
84
Q

When a peptide binds with sufficient affinity to HLA-2, ____ is displaced

A

CLIP

85
Q

As the HLA-2 containing vesicle merges with the phagosome/endosome containing the antigen, the invariant chain known as ____ is chopped up, and it will remain bound to the HLA-2 peptide binding region until displaced

A

CLIP

86
Q

HLA-2 with the bound extracellular antigen gets expressed on the ____

A

surface of the cell

87
Q

_____ helps with loading the antigen onto HLA-2

A

HLA-DM

88
Q

Under what exceptions can exogenous antigens be presented by HLA-1 and endogenous antigens presented by HLA-2?

A

1) an infected cell dies and is phagocytosed
- viral particles in the cytosol of infected cell will be presented on the HLA-2 of phagocyte (intracellular antigens become extracellular)
2) autophagy can result in peptides from cytosol being presented on HLA-2
3) cross-presentation
- blend of exogenous and endogenous pathways (i.e., dendritic cells and all APCs)
- allows APCs to either sequentially or simultaneously activate both T-helper and cytotoxic T cells
4) antigens can leak out of endosome after phagocytosis into the cytosol and be presented to HLA-1

89
Q

Once a peptide-bound HLA-2 is expressed on the surface of a cell, it can bind a ____ and activate it

A

CD4+ T-cell (helper T-cell)

90
Q

CD4 is the major co-receptor that distinguishes a _____ from a ____

A

T-helper cell
cytotoxic T-cell

91
Q

T-cells need a co-stimulatory activation, which is best represented by ___ on the T-cell with ___ on the APC

A

CD28
CD80/98

92
Q

What are the steps of T-cell activation with HLA-2?

A

1) T-cell receptor interacts with HLA-2
2) CD4 co-receptor interacts with HLA-2
3) CD28 interacts with CD80/86

93
Q

True or false: although most T-cells express CD28, most cells in the body do not express its ligands (CD80/86)

A

true

94
Q

Only professional APCs have the capacity to express ____

A

CD80/86

95
Q

What cells are the best activators of naive T-cells, and always express CD80/86s:

A

Mature dendritic cells

96
Q

Macrophages and B-cells have the capacity to ____ CD80/86, after they are activated by an encounter with a pathogen

A

upregulate

96
Q

How does CD28 signaling add to the effects of TCR signaling?

A

1) enhances the strength of signal between the T-cell and APC
2) initiates a cell-signaling cascade to promote T-cell survival and proliferation
- CD28 recruits PI3 kinase

96
Q

The two categories that the interactions between the T-cell and APC can be divided into are:

A

1) cSMAC (central supramolecular activation complex)
- TCR and HLA-2 (with co-activator CD4)
- Co-stimulator interaction (CD28 & CD80/86)
2) pSMAC (peripheral supramolecular activation complex)
- includes other receptor-ligand interactions that help strengthen the connection between the T-cell and APC to sustain the signal

97
Q

What else is involved in TCR and HLA-2 interactions and co-stimulatory interactions?

A

paracrine signaling between the APC and the T-cell

98
Q

Paracrine signaling between the APC and the T-cell help to polarize the helper T-cells, and this polarization depends on 2 factors:

A

1) the type of APC interacting with the T-helper cell
2) the cytokines present during the time of activation

99
Q

True or false: Co-stimulators are usually expressed at high levels on APCs

A

False
- Co-stimulators are usually NOT expressed at high levels on APCs

100
Q

HLA-2 and costimulatory expression increase only when the APC recognizes a ___ or a ___

A

DAMP
PAMP
- prevents unnecessary inflammation

101
Q

How does IL-2 serve as a growth factor for T-cells and B-cells?

A

1) proliferation and differentiation of activated naive T-cells
2) Proliferation and differentiation of B-cells

102
Q

Once activated, naive T-cells begin to synthesize IL-2 and the high-affinity forms the ____

A

IL-2 receptor

103
Q

IL-2 binding to the Th IL-2 receptor acts in an ____ fashion, and activates the Th cell and causes it to enter the cell cycle and avoid ____

A

autocrine
apoptosis

104
Q

True or false: Synthesis of both IL-2 and the high affinity IL-2 receptor is induced after CD28-CD80/88 binding and recognition of the antigen by the ___

A

TCR (via HLA-2)

105
Q

Ag recognition in absence of co-stimulation causes T cell ____

A

anergy

106
Q

True or false: Anergic T-cells cannot produce IL-2, which means they cannot proliferate and differentiate into effector cells when they encounter Ag

A

true

107
Q

What is the process of T-cell activation with IL-2?

A

1) naive T cells express the low affinity IL-2 receptor
2) activated T-cells express the high affinity IL-2 receptor and secrete IL-2
3) Binding of IL-2 to the high-affinity receptor sends a signal to the T-cell
4) The signal sent from the IL-2 receptor induces T-cell proliferation

108
Q

True or false: CD4 helper T-lymphocytes never kill pathogens or other “foreign-looking” entities directly

A

true

109
Q

How do helper T-cells aid immunity?

A

1) activate or inhibit other cells through direct contact (i.e., the immunologic synapse)
- CD8 cytotoxic T-cells, B-cells, macrophages
2) activate or inhibit other cells through the secretion of cytokines (influences a range of effectors)

110
Q

Helper T-lymphocytes that cause cells to differentiate after activation is known as ____

A

T-cell polarization

111
Q

Polarization is a specialized Th phenotype and the Th secretes a profile of ___ that mediate distinct effector cell functions

A

cytokines

112
Q

True or false: Th type is determined by the environment is it found in

A

true

BMS150 - Biomedicine (2 decks)

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