Sem 2: Immuno > Block 2 > Flashcards

Block 2 Flashcards

(75 cards)

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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
Macrophages are identified by expression of __________
CD14 CD11b F4/80
26
Which cell does NOT pocess granules but has lysosomes that contain factors required for killing
Macrophages
27
Macrophages react to ______ generated at sites of pathogen entry
Danger signals (SOS) Ex: 1. N-formyl-methionine 2. Peptides 3. Complement system 4. Cytokines
28
What are danger signals?
signals that alert and induce chemotaxis of macrophages to site of pathogen entry 1. N-formyl-methionine 2. Peptides 3. Complement system 4. Cytokines
29
What receptors do phagocytes possess to bind microorganisms?
1. Complement receptors 2. Scavenger receptors 3. Fc receptors 4. Toll-like Receptors (TLRs)
30
What are TLRs?
receptors on phagocytes that recognize PAMPs located on the host cell membranes OR within the host signals presence of invaders
31
What happens when macrophages bind antigens through TLRs?
They become activated and secrete cytokines like: 1. IL-1 2. 1L-6 3. TNF in prep for inflamm. rxn
32
What are Fc receptors?
Found on macrophages, ass. w phagocytosis Only used when antibodies are available, for example in a recurrent infection enhances activity of phagocyte
33
What is the purpose of phagocytosis?
1. Detect and destroy pathogens 2. Produce cytokines req. for inflamm rxn 3. Present antigens to induce immune response by lymphocytes
34
What are the steps of phagocytosis?
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
What killing pathways are used for neutrophils, monocytes and macrophages?
1. Oxidative pathway (ROS, RNS) 2. Non-oxidative pathway
36
What is the oxidative pathway of killing?
dependent on ROS and RNS Oxygen and glucose increases (respiratory burst)
37
Generation of ROS
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
What are some important ROS species?
H2O2 OH- Superoxide anion NADPH
39
Myeloperoxidase
released during fusion of azurophilic granules with the phagosome uses H202 and Cl- to make hypochlorous acid
40
Generation of RNS
Superoxide anion interacts with NITRIC OXIDE to make PEROXYNITRITE NITRIC OXIDE can also undergo oxidation to make RNS nitrogen dioxide
41
TNF alpha
induces expression of inducible nitric oxide synthetase (iNOS)
42
What does iNOS do?
Oxidises L arginine to yield L citrulline and nitric oxide (NO) ** NO highly toxic to bacteria
43
What induces iNOS?
TNF alpha and and IFNy
44
What are non oxidative mechanisms of killing?
1. Cationic proteins 2. Lysozymes 3. Lactoferrin 4. Proteolytic and hydrolytic enzymes
45
Cationic proteins
a non oxidative way of killing damages the bacterial cell wall
46
Lysozyme
a non oxidative way of killing damages mucopeptides in bacterial cell wall
47
Lactoferrin
a non oxidative way of killing sequestrates iron so bacteria cant grow
48
Proteolytic and hydrolytic enzymes
a non oxidative way of killing digests killed bacteria
49
Which are sentinel cells?
1. Macrophages 2. Mast cells 3. Dendritic cells they use PRRs to sense PAMPS and DAMPs
50
Pattern recognition receptors (PRRs)
they recognize PAMPs and DAMPs in the innate immune system
51
PAMPs
repetitive motif molecules expressed by microbial pathogens and not found on host tissues Ex of PAMPs: 1. Lipopolysaccharides 2. Peptidoglycans 3. Lipoteichoic acids
52
DAMPs
endogenous molecules released from damaged cells
53
What are some of the different classes of PRRs?
1. TLRs 2. NLRs 3. RLRs 4. CLRs 5. PGPs
54
What TLRs detect bacterial parasites?
TLR1 and TLR2
55
What TLRs detect gram + bacteria and fungi?
TLR2 + TLR6
56
What TLRs detect gram NEG bacteria?
TLR4
57
What TLRs detect flagellated bacteria?
TLR5
58
What TLR detects intracellular viral dsRNA (double stranded RNA)?
TLR3
59
What TLRs detects intracellular viral ssRNA (single stranded RNA)?
TLR7 + TLR8
60
What TLR detects intracellular bacterial DNA elements?
TLR9
61
How does signaling by TLRs occur?
All TLRs are signaled by MyD88 except TLR3 which signals through TRIF End point of signalling is to produce proinflamm. cytokines
62
What is a NLR?
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
What happens when NOD-like receptors detect PAMPs?
leads to activation of transcription factor NF-KB
64
NF-KB
activated when NOD like receptors detect PAMPs leads to transcription of genes responsible for expressing pro-inflamm. cytokines
65
NOD like receptors signal through _______ leading to production of _____________
IRF3/7 Type 1 interferons
66
What are RLRs?
Type of TLR Expressed in cytoplasm (intracellular) detects viral RNA (single and double) induces production of antiviral cytokines like IFNs and inflamm. cytokines
67
What are CLRs?
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
PGRPs
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
Where are PGRPs in pigs expressed?
In the skin, bone marrow, and intestines
70
What is the endpoint of TLR signalling?
Production of pro inflamm. cytokines like: PGEs, NO, TNFa, IL-1b, IL-6
71
Peyers patches are are considered PRIMARY lymphoid organs in what species?
Dogs, ruminants, pigs, rabbits similar function to Bursa of Fabricius
72
Peyers patches undergo involution in what species?
Rodents and rabbits
73
GALT/MALT
Inductive site- immune response induced Effector site- where cytolytic cells carry out the killing
74
What are enzymes involved with ROS?
1. superoxide anion 2. H2O2 3. O2 4. -OH (hydroxyl radical) 5. OH-
75
What enzymes are involved in RNS?
1. Superoxide anion 2. Nitric oxide 3. Peroxynitrite 4. nitrogen dioxide
Sem 2: Immuno
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