Innate Immunity

Question 1

Examples of mechanical factors (physical barriers)

Answer 1

skin, ciliary movement, peristalsis, washing by tears/saliva, mucus

Question 2

Examples of chemical factors (physical barriers)

Answer 2

fatty acids - inhibit bacterial growth
lysozymes and phospholipases - inhibit growth of infectious agents
low pH - antibacterial effects
surfactant - enhance phagocytosis

Question 3

microbiological factors (physical barriers)

Answer 3

healthy microbiome prevents infection by secreting inhibitory substances

Question 4

Beta-lysine

Answer 4

part of coagulative system, released by platelets, bactericidal

Question 5

Lactoferrin and transferrin

Answer 5

iron-sequestering molecules, prevent bacteria from stealing our iron

Question 6

lysozyme

Answer 6

digests the bacterial cell wall

Question 7

interferons

Answer 7

type I inhibit infection and replication of viruses

Question 8

interleukin 1

Answer 8

increases temp. in inflammation and induces acute phase proteins

Question 9

Neutrophils

Answer 9

most numerous innate immune cell, phagocytose and degrade pathogens. express CD66 marker.

Question 10

2 types of neutrophil granules

Answer 10

Azurophilic: defensins to kill bacteria, proteolytic enzymes such as elastase, cathepsin G to degrade bacterial proteins, lysozymes to digest bacterial cell wall, myeloperoxidase

Secondary granules: found only in mature neutrophils. contain lysozymes, lactoferrin, NADPH oxidase (produces toxic radicals)

Question 11

Macrophages

Answer 11

express CD14, CD11b, F4/80.
Kill with lysosomes. React to danger signals such as N-formyl-methionine, peptides of coagulative system, complement system, cytokines.

Question 12

Phagocyte receptors to bind pathogens

Answer 12

Fc receptors - bind Fc region of antibody
Complement receptor - bind C3b
Scavenger receptor - bind polyamines on bacterial surface
TLRs - bind to PAMPs

Question 13

Steps of phagocytosis

Answer 13

1. Chemotaxis
2. phagocyte detects and binds target
3. phagocyte surrounds target object and engulfs via endocytosis
4. endocytosed object enters a phagosome
5. phagolysosome forms
6. contents of lysosome released and digestion begins

Question 14

Oxidative pathway of killing

Answer 14

Production of ROS or RNS to destroy endocytosed object

Question 15

Non-oxidative pathway of killing

Answer 15

Cationic proteins - damages cell wall
Lysozyme - damage mucopeptides in cell wall
Lactoferrin - sequesters iron
Proteolytic and hydrolytic enzymes - digests bacteria

Question 16

TLRs

Answer 16

recognize many different PAMPs (intra and extracellular). produce proinflammatory cytokines

Question 17

NLRs

Answer 17

found only inside the cell, detect only intracellular pathogens or DAMPs
NOD1 - peptidoglycans
NOD2 - muramyl dipeptides
Causes activation of NFkB, leading to transcription of pro-inflammatory cytokines and IFNs.

Question 18

RLRs

Answer 18

expressed in cytoplasm, detect viral DNA, induce production of IFNs

Question 19

CLRs

Answer 19

bind carbs, involved in fungal recognition and immune modulation. Expressed by most cells

Question 20

PGRPs

Answer 20

recognize peptidoglycans, induce production of antimicrobial peptides like defensins
Constitutively expressed in pigs