20. Host Resistance

Question 1

2 types of immune system in vertebrates and difference?

Answer 1

Non-specific - heritable features that decrease probability of pathogen success

Specific - acquired as a result of lifetime of exposure to foreign agents (= unique to each individual)

Question 2

4 non-specific barriers to potential pathogens

Answer 2

1. Physical barriers
2. Chemical barriers
3. Phagocytosis
4. Inflammation

Question 3

3 physical barriers?

Answer 3

Lactoferrin

MALT (mucous-associated lymphoid tissue)

Mucociliary elevator

Question 4

What is lactoferrin?

Answer 4

Protein secreted in tears, saliva, milk

Present in WBC

Question 5

How does lactoferrin protect the host?

Answer 5

Chelates iron = keep [iron] low = decrease pathogen growth

Question 6

Where is MALT found?

Answer 6

Gut, conjunctiva (membranous layer on white of eye), respirator, urogenital tracts

Question 7

How does MALT protect the host?

Answer 7

Binds and samples foreign molecules

Stimulates specific immune system to produce specific antibodies

Question 8

What does MALT stand for?

Answer 8

Mucous-associated lymphoid tissue

Question 9

What is a goblet cell?

Answer 9

A mucous-producing cell

Question 10

Respiratory system => microbes >10µm are trapped by?

Answer 10

Hairs and cilia in nasal cavity

Question 11

Respiratory system => microbes

Answer 11

Mucociliary blanket (mucous and cilia that coat the lower portions of respiratory system)

Question 12

How does the mucociliary elevator work? Is it directional?

Answer 12

Ciliated epithelium beats upwards to move pathogens away from lungs

Yes

Question 13

What does lysozyme do? Where is it found?

Answer 13

Cleaves NAM-NAG bonds of peptidoglycan

In secretions

Question 14

3 chemical barriers?

Answer 14

Lysozyme

Anti-microbial peptides (defensins)

Complement protein cascade in blood

Question 15

What are defensins?

Answer 15

Short peptides (18-45 aa) that bind to+lyse foreign cells

Question 16

Where are defensins found?

Answer 16

Certain WBCs (neutrophils)

Epithelial cells in upper respiratory+intestinal tract

Question 17

What is the complement protein cascade in blood?

Answer 17

A series of ~30 proteins that are activated by the presence of foreign material

Question 18

2 phagocytes in blood?

Answer 18

Monocytes and polymorphonuclear leukocytes (PMNs)

Question 19

In tissues, monocytes that are always there are called..?

Answer 19

Resident macrophages

Question 20

What are resident macrophages called in the lower respiratory tract? In the liver?

Answer 20

Lower respiratory tract = alveolar macrophages

Liver = Kupffer cells

Question 21

What are PAMPs?

Answer 21

Pathogen-associated molecular patterns

Unique, conserved molecular structures on the microbe (not produced by host)

Question 22

What are PAMPs recognized by?

Answer 22

PRRs (pattern recognition receptors)

Question 23

What are PRRs?

Answer 23

Pattern recognition receptors => phagocytic cell receptors in the host cell

Question 24

What does the 1st step of phagocytosis involve?

Answer 24

Host PRR recognition of microbe PAMPs

Question 25

What does the 2nd step of phagocytosis involve?

Answer 25

Internalization into a phagosome Phagosome fusion with lysosomes to form a phagolysosome

Question 26

Microbe killing occurs in a structure called a ____________, which is a _______ fused with _________

Answer 26

phagolysosome phagosome fused with lysosomes

Question 27

What does TLR stand for?

Answer 27

Toll-like receptors

Question 28

How do TLRs function as signaling receptors (immunity wise)?

Answer 28

Once bound to a specific PAMP, TLRs trigger a signaling cascade that results in secretion of chemokines by macrophages

Question 29

3 examples of diseases that can survival lysosomal attack?

Answer 29

Legionnaires's disease and Pontiac fever, Salmonella infection

Question 30

2 examples of PAMPs?

Answer 30

LPS, peptidoglycan

Question 31

What are chemokines?

Answer 31

Small signaling molecules (chemotactic molecules) used to attract WBCs

Question 32

How big are chemokines?

Answer 32

8-10 kDa

Question 33

What does Legionella cause?

Answer 33

Legionnaires' disease (type of pneumonia => lung infection)

Question 34

What is Pontiac fever?

Answer 34

Milder infection (compared to Legionnaires') Caused by Legionella infection

Question 35

Legionella infections are phagocytosed by _____________

Answer 35

alveolar macrophages

Question 36

How do Legionella avoid lysosomal attack?

Answer 36

Once contained in a phagosome, secrets proteins into it that prevents phagosome maturation, recruits ER ER-containing phagosome is then protected from lysosomal attack and Legionella will replicate inside this protective phagosome

Question 37

How does Salmonella avoid lysosomal attack?

Answer 37

Salmonella found in SCV fuses with early endosmoes and then MODIFIES the vacuole by using bacterialy-derived proteins Lysosomes cannot penetrate the SCV

Question 38

2 serum proteins that are opsonins?

Answer 38

Antibodies Complement protein C3b

Question 39

What is phagocytosis inhibited by? Why?

Answer 39

Capsules They're EXTERNAL to the cell wall => macrophages cannot detect peptidoglycan/LPS

Question 40

What is phagocytosis enhanced by?

Answer 40

Coating foreign body with serum proteins to target them for destruction (=opsonization)

Question 41

What activates the complement cascade?

Answer 41

Abs and specific foreign molecules

Question 42

Example of a specific foreign molecule that activates the complement cascade?

Answer 42

Mannose polymers

Question 43

3 main outcomes of complement activation?

Answer 43

1. Opsonization => increases probability of phagocytosis 2. A complement protein acts as a chemokine and recruits WBCs 3. Complement proteins form a pore in a foreign cell and lyse it (mainly see this)

Question 44

Overall events in inflammation?

Answer 44

Redness (rubor) Heat (calor) Pain (dolor) Swelling (turgor)

Question 45

Where (on earth) do Legionella replicate?

Answer 45

Warm, stagnant water

Question 46

How does a Legionella infection occur?

Answer 46

By inhaling contaminated droplets (NOT person-to-person)