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BISC 303 > 20. Host Resistance > Flashcards

20. Host Resistance Flashcards

1
Q

2 types of immune system in vertebrates and difference?

A

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)

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2
Q

4 non-specific barriers to potential pathogens

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

3 physical barriers?

A

Lactoferrin

MALT (mucous-associated lymphoid tissue)

Mucociliary elevator

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4
Q

What is lactoferrin?

A

Protein secreted in tears, saliva, milk

Present in WBC

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5
Q

How does lactoferrin protect the host?

A

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

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6
Q

Where is MALT found?

A

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

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7
Q

How does MALT protect the host?

A

Binds and samples foreign molecules

Stimulates specific immune system to produce specific antibodies

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8
Q

What does MALT stand for?

A

Mucous-associated lymphoid tissue

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9
Q

What is a goblet cell?

A

A mucous-producing cell

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10
Q

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

A

Hairs and cilia in nasal cavity

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11
Q

Respiratory system => microbes

A

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

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12
Q

How does the mucociliary elevator work? Is it directional?

A

Ciliated epithelium beats upwards to move pathogens away from lungs

Yes

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13
Q

What does lysozyme do? Where is it found?

A

Cleaves NAM-NAG bonds of peptidoglycan

In secretions

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14
Q

3 chemical barriers?

A

Lysozyme

Anti-microbial peptides (defensins)

Complement protein cascade in blood

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15
Q

What are defensins?

A

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

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16
Q

Where are defensins found?

A

Certain WBCs (neutrophils)

Epithelial cells in upper respiratory+intestinal tract

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17
Q

What is the complement protein cascade in blood?

A

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

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18
Q

2 phagocytes in blood?

A

Monocytes and polymorphonuclear leukocytes (PMNs)

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19
Q

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

A

Resident macrophages

20
Q

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

A

Lower respiratory tract = alveolar macrophages

Liver = Kupffer cells

21
Q

What are PAMPs?

A

Pathogen-associated molecular patterns

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

22
Q

What are PAMPs recognized by?

A

PRRs (pattern recognition receptors)

23
Q

What are PRRs?

A

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

24
Q

What does the 1st step of phagocytosis involve?

A

Host PRR recognition of microbe PAMPs

25
Q

What does the 2nd step of phagocytosis involve?

A

Internalization into a phagosome

Phagosome fusion with lysosomes to form a phagolysosome

26
Q

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

A

phagolysosome

phagosome fused with lysosomes

27
Q

What does TLR stand for?

A

Toll-like receptors

28
Q

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

A

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

29
Q

3 examples of diseases that can survival lysosomal attack?

A

Legionnaires’s disease and Pontiac fever, Salmonella infection

30
Q

2 examples of PAMPs?

A

LPS, peptidoglycan

31
Q

What are chemokines?

A

Small signaling molecules (chemotactic molecules) used to attract WBCs

32
Q

How big are chemokines?

A

8-10 kDa

33
Q

What does Legionella cause?

A

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

34
Q

What is Pontiac fever?

A

Milder infection (compared to Legionnaires’)

Caused by Legionella infection

35
Q

Legionella infections are phagocytosed by _____________

A

alveolar macrophages

36
Q

How do Legionella avoid lysosomal attack?

A

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

37
Q

How does Salmonella avoid lysosomal attack?

A

Salmonella found in SCV fuses with early endosmoes and then MODIFIES the vacuole by using bacterialy-derived proteins

Lysosomes cannot penetrate the SCV

38
Q

2 serum proteins that are opsonins?

A

Antibodies

Complement protein C3b

39
Q

What is phagocytosis inhibited by? Why?

A

Capsules

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

40
Q

What is phagocytosis enhanced by?

A

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

41
Q

What activates the complement cascade?

A

Abs and specific foreign molecules

42
Q

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

A

Mannose polymers

43
Q

3 main outcomes of complement activation?

A
  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)
44
Q

Overall events in inflammation?

A

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

45
Q

Where (on earth) do Legionella replicate?

A

Warm, stagnant water

46
Q

How does a Legionella infection occur?

A

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

BISC 303 (22 decks)

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