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First Semester: Principles of Infectious Disease > Lecture 9: Host Defense I > Flashcards

Lecture 9: Host Defense I Flashcards

1
Q

Innate response

A

Functions in normal host without prior exposure to invading microbes

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2
Q

Adaptive response consists of what responses

A

Antibody response (humoral) and lymphocyte mediated response (cell-mediated) response - tailored to particular microbial infection and characterized by memory

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3
Q

Adaptive immunity

A

adaptive, specific immune responses are induced by exposure to an antigen, the response is specific for the inducing antigens and immunologic memory is generated

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4
Q

5 factors of innate immunity

A
  • Constitutional factors
  • Natural barriers and normal flora
  • Cytokines/Interferons
  • Phagocytosis
  • Complement
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5
Q

Constitutional factors

A

Making one species innately susceptible and another resistant to certain infections

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6
Q

Examples of constitutional factors

A
  • Genetic: between species
  • Age: young more susceptible
  • Metabolic factors: hypoadrenal and hypothyroid states
  • Neuroendocrine factors
  • Environment - malnutrition, poor living conditions, overcrowding
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7
Q

Normal flora =

A

Colonization resistance, competition for attachment sites and for essential nutrients

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8
Q

Major functions of Type I Interferons (IFN)

A
  • Induce resistance to viral replication in all cells
  • Increase MHC class I expression and antigen presentation in all cells
  • Activate NK cells to kill virus-infected cells
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9
Q

IFN is demonstrated in

A

animal models

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10
Q

Defective IFN response

A
  • Reduced ability to contain infection

- Increased illness and death

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11
Q

Abrogation of IFN - a/b

A
  • Global increase in susceptibility

- IFN - y -modest effect

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12
Q

Phagocytosis

A

Engulfment and digestion of infectious agents or other foreign bodies by phagocytic cells

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13
Q

Phagocytic cells

A
  • Phagocytes

- Neutrophil

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14
Q

5 steps of phagocytosis

A
  1. Bacterium becomes attached to membrane
  2. Bacterium is ingested, forming phagosome
  3. Phagosome fuses with lysosome
  4. Lysosomal enzymes digest captured material
  5. Digestion products are released from the cell
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15
Q

Receptors of innate immune system

A
  • Pattern recognition receptors

- Missing/altered self receptors (NK cells)

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16
Q

3 types of pattern recognition cells

A
  • Toll like receptors (TLRs)
  • Rig like receptors (RLR)
  • Complement
17
Q

Adaptive immune system

A
  • Antigen presentation (MHC)
  • Antibodies
  • T cell receptors
18
Q

PRR (toll like receptors) recognizes

A

Pathogen-associated molecular patterns

19
Q

Mediators of antimicrobial and cytotoxic activity of macrophages and neutrophils
Oxygen-independent killing

A
  • Defensins
  • Tumor necrosis factor alpha (macrophage only)
  • Lysozome
  • Hydrolytic enzymes (acid hydrolases)
20
Q

Neutrophils

A

Primarily function to phagocytize and kill extracellular bacterial and yeast pathogens in acute inflammation

21
Q

Neutrophils live

A

Only 1 day in the tissues

22
Q

Dead neutrophils are cleaned up by

A

macrophages

23
Q

Leukocytosis

A

Granulocytosis involving neutrophils = bacterial infections

24
Q

Typical scenario for acute inflammatory response involving neutrophils

A
  • Large reserves of neutrophils are stored within the bone marrow and are released when they’re needed to fight infection
  • Neutrophils travel to and enter the infected tissue, where they engulf and kill bacteria.
  • The neutrophils die in the tissue and are engulfed and degraded by macrophages
25
Q

Eosinophils are 1-3%

A

WBC but #’s increase in parasite infections and patients with type I hypersensitivities

26
Q

Eosinophils are important against the defense against

A

helminths

27
Q

Abundant lymphocytes- ___% of circulating

A

2

28
Q

Large, granular lymphocytes lack

A

antigen-specific receptors found on T and B cells

29
Q

Number of natural killer cells increases rapidly after

A

viral infection

They’re stimulated to divide by IFN produced by infected cells and dendritic cells

30
Q

On binding, lymphocytes release

A

a mix of cytokines (IFN y and TNF a)

31
Q

How do natural killer cells kill cells?

A

Releasing perforins and granzymes - perforate membranes and trigger caspase - mediated cell death

32
Q

How do NK cells recognize infected cells?

A

Detection of altered self

First Semester: Principles of Infectious Disease (22 decks)

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