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Sem 2: Immuno > Block 2 > Flashcards

Block 2 Flashcards

1
Q

What is the function of lymphnodes?

A

facilitates interaction between dendritic cells and antigen-sensitive T and B lymphocytes

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2
Q

What are characteristics of white pulp?

A
  • rich in lymphocytes

-where immune induction occurs

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3
Q

What is the primary functions of the spleen?

A

filters blood for blood-borne antigens, cellular debris and aged blood cells

stores RBCs, PLTs, and recycles iron

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4
Q

What is innate immunity?

A
  • Non specific
  • Fast
  • No memory

Present @ birth

protects body from infection without prior contact w infectious agent

Physical Barriers (skin, MM)
Humoral Barriers (complement system)
Cellular Barriers (Phagocytic, NK cells)

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5
Q

What is adaptive immunity?

A
  • Specific
  • Delayed response
  • Memory present
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6
Q

What is the first line of defense?

A

Physical barriers- Skin, mucus membranes, chemicals

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7
Q

What is the 2nd line of defense?

A

Phagocytosis, complement, interferons, inflammation, fever

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8
Q

What is the 3rd line of defense?

A

Adaptive immunity

Lymphocytes and antibodies

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9
Q

What are the mechanical factors associated with physical barriers of innate immunity?

A
  1. Skin
  2. Ciliary movement (resp. tract)
  3. Peristaltic movement (in SI + LI)
  4. Washing (by tears + saliva)
  5. Mucus layer

All of theses defend body by mechanically removing infectious agents and preventing entry

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10
Q

What are the chemical factors associated with physical barriers of innate immunity?

A
  1. Fatty acids- SWEAT inhibits bacteria growth
  2. Lyzozyme + Phospholipase (in tears/sweat)
  3. Low pH of sweat
  4. Surfactants (Opsonins in lungs! Enhances phagocytosis)
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11
Q

What are the microbiological factors associated with physical barriers of innate immunity?

A

Normal biota on skin and digestive tract prevents infection by secreting inhibitory substances

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12
Q

What is the most important humoral factors of innate immunity?

A
  1. Complement system!
  2. Coag system
  3. Lactoferrin and transferrin
  4. Lysozyme
  5. Interferons
  6. Interleukin 1
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13
Q

What is the coag system responsible for in innate immunity?

A

a Humoral barrier

if activated, leads to coagulation at damage site

some molecules act as CHEMOTACTIC FACTORS that attract other cells to site of damage

Beta-lysine made by platelets has bacteriocidal effects on gram + bacteria

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14
Q

What does Beta-Lysine do?

A

made by PLTs

Kills Gram + bacteria during the coagulation process

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15
Q

What does lactoferrin and tranferrin do?

A

binds iron so bacteria cant grow

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16
Q

Interleukin 1

A

Humoral barrier of innate immunity

increases temp during inflammation and induces acute phase proteins that are bacteriocidal

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17
Q

What cells are part of the cellular barrier of innate immunity?

A
  1. Neutrophils
  2. Macrophages
  3. NK cells
  4. Eosinophils
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18
Q

What are the most IMPT cells on innate immunity?

A
  1. Neutrophils
  2. Macrophages
  3. Dendritic cells
  4. NK cells
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19
Q

What are the vital cells of the phagocytic system?

A

Neutrophils and macrophages

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20
Q

Which granules do neutrophils require for intracellular killing?

A
  1. Azurophilic granules
  2. Secondary granules
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21
Q

Azurophilic granules

A

Granules found in neutrophils

Contains:
1. DEFENSINS that kill bacteria

  1. PROTEOLYTIC ENZYMES like ELASTASE and CATHEPSIN G
  2. LYZOZYMES that degrade bacteria cell wall
  3. MYELOPEROXIDASE for generation of bactericidal substances
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22
Q

Secondary granules

A

Granules found in neutrophils

Contains:
1. LYZOZYMES that degrade bacteria cell wall

  1. LACTOFERRIN that binds iron so bacteria cant grow
  2. NADPH oxidase that produces toxic radicals
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23
Q

What is the function of proteolytic enzymes?

A

Degrades bacterial proteins

Found in azurophilic granules in neutrophils

Ex: Elastase and Cathepsin G

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24
Q

Neutophils are identified by expression of _________

A

CD66 on cell surface

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25
Q

Macrophages are identified by expression of __________

A

CD14

CD11b

F4/80

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26
Q

Which cell does NOT pocess granules but has lysosomes that contain factors required for killing

A

Macrophages

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27
Q

Macrophages react to ______ generated at sites of pathogen entry

A

Danger signals (SOS)

Ex:
1. N-formyl-methionine
2. Peptides
3. Complement system
4. Cytokines

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28
Q

What are danger signals?

A

signals that alert and induce chemotaxis of macrophages to site of pathogen entry

  1. N-formyl-methionine
  2. Peptides
  3. Complement system
  4. Cytokines
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29
Q

What receptors do phagocytes possess to bind microorganisms?

A
  1. Complement receptors
  2. Scavenger receptors
  3. Fc receptors
  4. Toll-like Receptors (TLRs)
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30
Q

What are TLRs?

A

receptors on phagocytes that recognize PAMPs

located on the host cell membranes OR within the host

signals presence of invaders

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31
Q

What happens when macrophages bind antigens through TLRs?

A

They become activated and secrete cytokines like:

  1. IL-1
  2. 1L-6
  3. TNF

in prep for inflamm. rxn

32
Q

What are Fc receptors?

A

Found on macrophages, ass. w phagocytosis

Only used when antibodies are available, for example in a recurrent infection

enhances activity of phagocyte

33
Q

What is the purpose of phagocytosis?

A
  1. Detect and destroy pathogens
  2. Produce cytokines req. for inflamm rxn
  3. Present antigens to induce immune response by lymphocytes
34
Q

What are the steps of phagocytosis?

A
  1. Chemotaxis
  2. Phagocytes detect and bind to target
  3. They surround the captured target w pseudopodia and engulf through endocytosis
  4. Endocytosed object becomes enclosed in phagosome
  5. Phagosome fuses w lysosome = phagolysosome
  6. Contents of lysosome released into phagolysosome
  7. Digestion begins
35
Q

What killing pathways are used for neutrophils, monocytes and macrophages?

A
  1. Oxidative pathway (ROS, RNS)
  2. Non-oxidative pathway
36
Q

What is the oxidative pathway of killing?

A

dependent on ROS and RNS

Oxygen and glucose increases (respiratory burst)

37
Q

Generation of ROS

A
  1. Glucose metabolized through pentose-phosphate leads to NADPH
  2. Cytochrome oxidase activates NADPH
  3. NADPH uses O2 to produce SUPEROXIDE ANION
  4. Superoxide anion reduces to H2O2 and O2

OR superoxide anion reacts with H2O2 to produce hydroxyl (OH-) and ions

38
Q

What are some important ROS species?

A

H2O2

OH-

Superoxide anion

NADPH

39
Q

Myeloperoxidase

A

released during fusion of azurophilic granules with the phagosome

uses H202 and Cl- to make hypochlorous acid

40
Q

Generation of RNS

A

Superoxide anion interacts with NITRIC OXIDE to make PEROXYNITRITE

NITRIC OXIDE can also undergo oxidation to make RNS nitrogen dioxide

41
Q

TNF alpha

A

induces expression of inducible nitric oxide synthetase (iNOS)

42
Q

What does iNOS do?

A

Oxidises L arginine to yield L citrulline and nitric oxide (NO)

** NO highly toxic to bacteria

43
Q

What induces iNOS?

A

TNF alpha and and IFNy

44
Q

What are non oxidative mechanisms of killing?

A
  1. Cationic proteins
  2. Lysozymes
  3. Lactoferrin
  4. Proteolytic and hydrolytic enzymes
45
Q

Cationic proteins

A

a non oxidative way of killing

damages the bacterial cell wall

46
Q

Lysozyme

A

a non oxidative way of killing

damages mucopeptides in bacterial cell wall

47
Q

Lactoferrin

A

a non oxidative way of killing

sequestrates iron so bacteria cant grow

48
Q

Proteolytic and hydrolytic enzymes

A

a non oxidative way of killing

digests killed bacteria

49
Q

Which are sentinel cells?

A
  1. Macrophages
  2. Mast cells
  3. Dendritic cells

they use PRRs to sense PAMPS and DAMPs

50
Q

Pattern recognition receptors (PRRs)

A

they recognize PAMPs and DAMPs in the innate immune system

51
Q

PAMPs

A

repetitive motif molecules expressed by microbial pathogens and not found on host tissues

Ex of PAMPs:
1. Lipopolysaccharides
2. Peptidoglycans
3. Lipoteichoic acids

52
Q

DAMPs

A

endogenous molecules released from damaged cells

53
Q

What are some of the different classes of PRRs?

A
  1. TLRs
  2. NLRs
  3. RLRs
  4. CLRs
  5. PGPs
54
Q

What TLRs detect bacterial parasites?

A

TLR1 and TLR2

55
Q

What TLRs detect gram + bacteria and fungi?

A

TLR2 + TLR6

56
Q

What TLRs detect gram NEG bacteria?

A

TLR4

57
Q

What TLRs detect flagellated bacteria?

A

TLR5

58
Q

What TLR detects intracellular viral dsRNA (double stranded RNA)?

A

TLR3

59
Q

What TLRs detects intracellular viral ssRNA (single stranded RNA)?

A

TLR7 + TLR8

60
Q

What TLR detects intracellular bacterial DNA elements?

A

TLR9

61
Q

How does signaling by TLRs occur?

A

All TLRs are signaled by MyD88

except TLR3 which signals through TRIF

End point of signalling is to produce proinflamm. cytokines

62
Q

What is a NLR?

A

A type of TLR, found INSIDE cells

Detects INTRACELLULAR pathogens in the cytoplasm

NOD1 detects bacterial peptidoglycans
NOD2 detects muramyl dipeptides

activated by non-microbial danger signals released by DAMPs

63
Q

What happens when NOD-like receptors detect PAMPs?

A

leads to activation of transcription factor NF-KB

64
Q

NF-KB

A

activated when NOD like receptors detect PAMPs

leads to transcription of genes responsible for expressing pro-inflamm. cytokines

65
Q

NOD like receptors signal through _______ leading to production of _____________

A

IRF3/7

Type 1 interferons

66
Q

What are RLRs?

A

Type of TLR

Expressed in cytoplasm (intracellular)

detects viral RNA (single and double)

induces production of antiviral cytokines like IFNs and inflamm. cytokines

67
Q

What are CLRs?

A

Type of TLR

Fungal recognition and modulates innate immune response

has receptors that bind to CARBS in CALCIUM DEPENDENT manner

expressed by most cells (macrophages, dendritic cells)

68
Q

PGRPs

A

localized in the large granules of NEUTROPHILS

detects peptidoglycan which induces production of antimicrobial peptides like defensins

alternating NAG and NAMs found on Gram + and - bacteria

69
Q

Where are PGRPs in pigs expressed?

A

In the skin, bone marrow, and intestines

70
Q

What is the endpoint of TLR signalling?

A

Production of pro inflamm. cytokines like:

PGEs, NO, TNFa, IL-1b, IL-6

71
Q

Peyers patches are are considered PRIMARY lymphoid organs in what species?

A

Dogs, ruminants, pigs, rabbits

similar function to Bursa of Fabricius

72
Q

Peyers patches undergo involution in what species?

A

Rodents and rabbits

73
Q

GALT/MALT

A

Inductive site- immune response induced

Effector site- where cytolytic cells carry out the killing

74
Q

What are enzymes involved with ROS?

A
  1. superoxide anion
  2. H2O2
  3. O2
  4. -OH (hydroxyl radical)
  5. OH-
75
Q

What enzymes are involved in RNS?

A
  1. Superoxide anion
  2. Nitric oxide
  3. Peroxynitrite
  4. nitrogen dioxide

Sem 2: Immuno (17 decks)

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