L13 Innate Immunity Flashcards

1
Q

What is innate immunity

A

Immediate response to a pathogen that does not confer long lasting protective immunity.
Non specific defense system

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2
Q

What Are the 3 phases of response to initial infection

A

Innate immunity(0-4 hrs)
Early induced innate response(4-96hrs)
Adaptive immune response(>96 hrs)

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3
Q

What are innate immune mechanisms

A

Act immediately

Followed by early induced responses which can be activated by infection but do not generate lasting protective immunity

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4
Q

When would adaptive immunity occur

A

Only if an infectious organism can breach these lines of defense will an adaptative immune response ensue with the generation of antigen specific effector cells that specifically target the pathogen and memory cells that can prevent reinfection with the same microorganism

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5
Q

What are the cells of innate immunity

A
Neutrophils 
Monocytes 
Natural killer cells
Eosinophils 
Basophils
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6
Q

First responders to infection and phagocytose bacteria in to phagosomes before hydrolyzing and destroying them

A

Neutrophils

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7
Q

Rapid response and not prolonged effect

A

Neutrophils

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8
Q

Phagocytose pathogens

A

Macrophages

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9
Q

When do monocytes become macrophages

A

When they are in tissues

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10
Q

Provide prolonged defense

A

Monocytes

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11
Q

What are natural killer cells and what do they do

A

Large granular lymphocytes that recognize non specifically the surface changes on tumor cells and virus infected cells and damage these cells without prior sensitization

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12
Q

Cells that fail to express MHC class 1 molecules

A

Natural killer cells

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13
Q

What is the process of ADCC and which cell carries it out

A

Natural killer cell

Binding to antibody already attached to antigen on a target cell using their Fc receptors

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14
Q

Naturally present in spleen and peripheral blood

A

Natural killer cells

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15
Q

Have granules containing a variety of enzymes and toxic proteins which are released when these cells are activated

A

Eosinophils and basophils

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16
Q

Which cells are Important against defense of parasites and why

A

Eosinophils and basophils as they are too large to be ingested by macrophages or neutrophils

17
Q

What are the barriers to infection

A

Epithelial layers

Antimicrobial substances

18
Q

Where are epithelial cells a barrier and how

A
Skin 
Airways
GIT
Genitourinary tract
Have tight junctions and produces a number antimicrobial peptides that help provide protection against invading pathogens
19
Q

What are the antimicrobial substances

A

Lysozyme
Defensins
Lactoferrin

20
Q

What is the lysozyme and what does it do

A

Tears mucus saliva

Splits the sugar from the mucopeptide layer of the cell wall of gram positive bacteria

21
Q

What are defensins and what do they do and where are they produced

A

Peptides produced by neutrophils epithelial cells and other cells that disrupt microbial membranes
Primarily produced in GIT and lower respiratory tract that create pores in lipid membranes of bacteria fungi and some viruses

22
Q

What is lactoferrin and what does it

A

Iron binding protein

Deprives micorbes of the free iron they need for growth

23
Q

How does mucous protect

A

Trapping mechanism
And action of cilia sweeps secretion with inhaled microorganisms either outside through coughing and sneezing or towards stomach where they are acted upon by hcl

24
Q

Describe phagocytosis

A

1–phagocytic cells engulf microorganisms and remove them from lymph and blood stream
2-phagosome containing microbe fuses with lysosome
3-microbe is killed within phagolysosome by proteases as well as by reactive oxygen species and reactive nitrogen radicles

25
Q

How can phagocytosis be enhanced

A

enhanced by opsonization of the particles by opsonin which include complement fragments C3b and IgG

26
Q

What are the pattern recognition receptors of innate immunity cells

A

Toll like receptors

Nucleotide binding oligomerization like receptors

27
Q

What are toll like receptors

A

They are a group of pattern recognition receptors found either on the surface or in the endosomal compartment of innate immune cells such as macrophages and dendritic cells they are glycoprotein in nature and are an important part of innate immunity

28
Q

What do toll like receptors recognize and bind to

A

they recognize and bind to highly conserved structures present in different organisms known as pathogen associated molecular patterns

29
Q

What do PAMPs include

A

1-Bacterial components as flagellant peptidoglycan Tiechoic cells lipopolysaccharides
2-Fungal molecules as zymosan and mannas
3-viral molecules as viral nucleic acid and proteins

30
Q

What do cell surface TLRs sense

And what do those in endosomal compartment bind to

A

Cell surface TLR‘s typically sense PAMPS of microbial cell envelopes flagella or Lipopolysaccharide
In the endosomal compartment bind to nucleic acids

31
Q

What happens after binding of TLRs to PAMPS of bacteria and fungi

A

Triggers the activation of signal transduction pathways resulting in the activation of innate immune cells and synthesis of cytokines as IL2 IL8 and TNFa that in turn triggers immune defenses as inflammation,fever and phagocytosis
binding of TLRs to viral components trigger synthesis of interferon and blocks viral replication

32
Q

Describe nucleotide binding oligomerization domain like receptors

A

They are specialized set of intracellular cytosolic receptors that are essential components of the innate immune system and function by the recognition of cytoplasmic PAMPS resulting in activation of signaling pathways

33
Q

What is the result of NLRS activating signaling pathways

A

Production of cytokines and chemokines which alert the immune system to the presence of pathogenic bacteria and Aid in the clearance of infection

34
Q

What is inflammation

A

Acute local inflammation as an early defense mechanism to contain the infection prevent its spread from the initial focus and activates subsequent immune response

35
Q

How does fever protect organism snd how is it triggered

A

Triggered by resetting hypothalamic thermostat triggered by toxins or cytokines
The higher temperature inhibit bacterial growth intensifies the effect of antiviral interferons and speeds of the body‘s reaction aiding tissue repair

36
Q

Complement system

A

It is another key component of innate immunity the alternative and lectin pathways of complement activation serve as critical first line of defense and provide immediate protection against microorganisms