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Infection and Immunity > Innate Immunity > Flashcards

Innate Immunity Flashcards

1
Q

What are some exterior physical and chemical defenses

A
  • Lysozyme in tears and other secretions
    -commensals
  • removal of particles by the rapid passage of air over turbinate bones
  • Bronchi (mucus and cilia)
    -Gut (acid, rapid ph change, commensals)
    -flushing of the urinary tract
    -low ph and commensals of the vagina
    -skin (physical barrier, fatty acids, commensals)
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2
Q

What do lysosomes do to bacteria

A

-They digest the cell wall of gram + and gram -ve bacteria
- cleaves B-(1-4) linkages between sugar molecules.

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3
Q

What are the mechanical, chemical, and microbiological defenses against infection found in skin

A

-Mechanical
epithelial cells joined by tight junctions
the longitudinal flow of air or fluid
-Chemical
Fatty acids
B- defensins lamellar bodies cathelicidin
-Microbiological
normal microbiota

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4
Q

What are the mechanical, chemical, and microbiological defenses against infection found Gut

A

-Mechanical
Epithelial cells joined by tight junctions
The longitudinal flow of air or fluid
-Chemical
Low pH
Enzymes (pepsin)
a-defensins (cryptdins)
Regll (lecticidins)
cathelicidin
-Microbiological
normal microbiota

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5
Q

What are the mechanical, chemical, and microbiological defenses against infection found Lungs

A

-Mechanical
Epithelial cells joined by tight junctions
movement of mucus by cilia
-Chemical
Pulmonary surfactant
a-defensins cathelicidin
-Microbiological
normal microbiota

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6
Q

What are the mechanical, chemical, and microbiological defenses against infection found Eyes/nose/oral cavity

A

-Mechanical
epithelial cells joined by tight junctions
Tears nasal cilia
-Chemical
enzymes in tears and saliva (lysozyme)
histatins b-defensins
-Microbiological
normal microbiota

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7
Q

What cells in the intestine produce antimicrobial proteins and which ones are produced?

A

The paneth cells found in epithelial crypts
they produce a-defensins (cryptdins) and the antimicrobial lectin RegIII

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8
Q

What are a-defensins?

A

amphipathic peptides that disrupt the cell membranes of microbes by inserting into the lipid bilayer. This leads to the formation of pores in the membrane and thus the membrane loses its integrity and collapses, leading to the death of the microbe.

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9
Q

What is the anti-microbial defensins, RegIIIy?

A

It is a C-type lectin that binds to peptidoglycans on bacterial cell walls. It mostly kills gram-positive bacteria

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10
Q

What results in the development of inflammatory bowel diseases (IBD)?

A

The immune system reacts with potentially pathogenic microbes while at the same time remaining ignorant of the non-pathogenic microbiota. The disruption of this delicate balance results in the development of IBD

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11
Q

What happens when there are not enough commensal “friendly” bacteria in the gut lumen?

A

-The colon contains lots of commensals
- Antibiotics kill many of the commensal bacteria
- Pathogenic bacteria increase in number in that area and produce toxins that cause mucosal injury
- Red and white blood cells leak into the gut between injured epithelial cells

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12
Q

What are the primary and secondary lymphoid organs and what do they produce?

A
  1. Primary lymphoid organs
    - Bone marrow- produces white blood cells
    - Thymus- helps with T cell development
  2. Secondary lymphoid organs
    -lymph nodes
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13
Q

Give examples of lymphocytes and their soluble mediators.

A
  1. B cell- antibodies
  2. T cell- cytokines
  3. Large granular lymphocyte- cytokines
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14
Q

Give an example of phagocytes and their soluble mediators?

A
  1. monoclear phagocyte- cytokines and complements
  2. neutrophil
  3. eosinophil
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15
Q

Give an example of auxiliary cells and their soluble mediators?

A
  1. basophil- inflammatory mediators
  2. mast cells- inflammatory mediators
  3. platelets- inflammatory mediators
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16
Q

what are the soluble mediators for tissue cells?

A
  1. interferons
  2. cytokines
17
Q

what are the four Latin words that describe inflammation?

A

calor= heat
dolor=pain
rubor=redness
tumor=swelling

18
Q

what causes the effects of inflammation?

A

The effects are all due to the action of local cytokines made by white blood cells in the infected tissue (such as after a splinter in the finger) which affects the local blood vessels.

19
Q

What happens when an infection triggers an inflammatory response?

A
  • bacteria trigger macrophages to release cytokines and chemokines
  • vasodilation and increased vascular permeability cause redness, heat, and swelling
  • inflammatory cells migrate into the tissue, releasing inflammatory mediators
20
Q

What process do white blood cells use to migrate into a tissue?

A

extravasation

21
Q

describe phagocytosis?

A

-phagocytes arrive at a site of inflammation by chemotaxis. The infectious agent is then taken into the phagosome by pseudopodia extending around it.
- once inside, the lysosomes fuse with the phagosome to form a phagolysosome and the pathogen is killed. Some antigenic peptides will then be displayed on the membrane cell surface in the groove of an MHC Class II molecule.

22
Q

What are the three types of antigen-presenting cells?

A
  1. Dendritic cells
  2. Macrophages
  3. B lymphocytes
23
Q

What do macrophages and DC cells express?

A

receptors for many antigenic structures found on a range of pathogens

24
Q

What do mannose, glucan, and scavenger receptors bind?

A

Cell wall carbohydrates of bacteria, yeast, and fungi

25
Q

What Toll-like receptors (TLRS) do?

A

TLRS can recognize if a bacterium is gram-positive (such as the TLR-1: TLR-2 dimer) or gram-negative bacteria (TLR-4 sees LPS)

26
Q

What do NOD-like receptors do?

A

sense bacteria that have invaded the inside of the cell so are found in the cytoplasm

27
Q

How do dendritic cells initiate the adaptive immune response?

A

They do this by taking up antigens in infected tissues such as the skin and then moving to a local lymph node to activate resting T helper cells ( naive T cells that have never seen antigen)

28
Q

Describe opsonisation?

A
  • Bacteria is coated with complement and IgG antibody
  • When C3b binds to CR1 and the antibody binds to the FC receptor, bacteria are phagocytosed
  • Macrophage membranes fuse, creating a membrane-enclosed vesicle, the phagosome
  • Lysosomes fuse with these vesicles, delivering enzymes that degrade the bacterium
29
Q

What does the binding to Fc receptors and complement receptors do?

A

It signals the fusion of lysosomes (filled with enzymes) with phagosomes and increases bactericidal activity.

30
Q

What are the escape strategies some bacterial species have to counter macrophage activity against them? (6)

A
  1. Toxin release
    organism releases toxins that kill phagocyte e.g. staphylococci, streptococci, amebae
  2. Opsonization prevented
    organism (e.g. staphylococci) produces a protein (e.g protein A) which prevents interaction between opsonizing antibody and phagocyte, so preventing phagocytosis
  3. Contact with phagocytes prevented
    the organism possesses a capsule that prevents contact with the phagocyte, e.g. Streptococcus pneumoniae, Haemophilus, bacillus anthracis
  4. Phagolysosome fusion inhibited
    Fusion of phagosome and lysosome inhibited by the organism, e.g. mycobacterium tuberculosis, toxoplasma, chlamydia
  5. Escape into the cytoplasm
    organism escapes from the phagolysosome into the cytoplasm and replicates within the phagocyte, e.g leishmania T.cruzi
  6. Resistance to killing
    organism resists killing by producing antioxidants, e.g by catalase in staphylococci, or by scavenging free radicals, e.g. by phenolic glycolipid of M. leprae

Infection and Immunity (1 decks)

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