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Immunology > Innate Immune System > Flashcards

Innate Immune System Flashcards

1
Q

What is immunology

A

The study of immunity

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2
Q

What is immunity

A

The body’s ability to protect itself against pathogens, itself, stopping irregular cell growth, toxins, mistakes in cell replication etc

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3
Q

What is a pathogen

A

A disease producing organism

Virus, bacteria, prion, Protozoa, helminth

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4
Q

What are some situations in which an understanding of how the immune system works is beneficial

A

Vaccinations
Disease processes (allergies)
Medications
Testing

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5
Q

True or false

Immunity and host defence mean the same thing

A

True

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6
Q

Describe the innate immune system and give an example

A

Non specific
Rapid
Consistent
Already exists in the body at birth

ex. Barriers, phagocytes, complement system, chemical barriers, physical barriers, rapid responders

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7
Q

What does it mean by the innate immune system being non specific

A

It does not change with repeated exposure, it always gives the same response

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8
Q

Describe the adaptive immune system

A

Specific
Discriminatory (self and non-self)
Has memory

Adapts to the situation in the body, and learns from previous exposures

Can be slow or rapid depending on if it’s been exposed to the pathogen before

Consists of specialist responders (respond to specific threats)

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9
Q

What are the 2 types of the adaptive immune system

A

Humoral mediated (bodily fluids)

Cellular mediated

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10
Q

What cells specialize in problems outside the cells

A

Phagocytes, complement system, antibodies

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11
Q

What cells specialize in problems within the cell

A

NK lymphocytes
Interferons
T lymphocytes

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12
Q

What is the innate immune system divided into

A

Fixed defences and mobile defences

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13
Q

What are the main fixed (external) defences of the innate immune system

A 
Chemical barriers (gastric pH)
Physical barriers (skin)
Traps (nasal secretions)
Elimination (coughing, urination) 
Commensal bacteria 
Antimicrobial chemicals (lysozyme, defensins)
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14
Q

What is lysozyme

A

Antimicrobial enzyme that digests cell walls

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15
Q

What are defensins

A

Antimicrobial proteins produced by epithelial cells and neutrophils. These make pores in cells walls of bacteria/fungi/viruses to allow them to lyse

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16
Q

Describe the innate (fixed) immune system found in hair and skin

A

Lubricated/protected by sebum (fatty acid that lowers pH)

Defensins (antimicrobial protein made by keratinocytes)

Commensal bacteria (fatty acids)

Tough and inert

Constantly shed

Tough, flexible, and resistant to chemicals

Repair of wounds (close openings to bacteria)

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17
Q

Describe the innate (fixed) immune system of the nose

A

Hairs (acts as a filter to trap pathogens so they are not inhaled)

Turbinates

Mucus (sticky, contains lysozyme)

Commensal bacteria

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18
Q

Describe the innate (fixed) immune system of the trachea

A

Cilia (tiny hairs sweep things out of the trachea) (mucociliary elevator) (physical structure)

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19
Q

What are some examples of physiological barriers

A

Tears
Blinking
Coughing
Sneezing

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20
Q

What is the innate (fixed) immune system of the stomach

A

Acidity of stomach acid (kills many pathogens)

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21
Q

What medicine interferes with the stomach acidity and can prevent normal protection from pathogens in this area

A

Antacids, ulcer prevention meds, these all decrease the acidity of the stomach acid (increase pH)

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22
Q

What is the innate (fixed) immune system of the small intestine

A

Sudden pH change from highly acidic to highly alkaline

Peristalsis (will move faster to remove pathogens)

Gut flora (compete for nutrients, produce antibacterial compounds)

Defensins

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23
Q

What medications interfere with the defences of the small intestine

A

Antibiotics (these target all bacteria, including good ones) or anything that slows down peristalsis

(This is why probiotics are used to replace bacteria)

These kill of all the good bacteria as well, allowing for the harmful bacteria to take over

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24
Q

Describe how blinking protects the eye

A

Physiological response

Protects from trauma and drying out

Tears: good for flushing and they contain lysozyme

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25
Q

What is keratoconjunctivitis sica (KCS)

A

DRY EYE

due to a lack of tears, makes the eye more prone to infection and ulcers

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26
Q

Describe the innate immune system of the urogenital tract

A

Flushing of the urinary tract

Vagina: Commensal bacteria, lactic acid (highly acidic to protect from infection)

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27
Q

What are some innate mobile defences

A

Phagocytes (neutrophils and macrophages/monocytes)

Killer (NK) lymphocytes

Complement system

Interferons

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28
Q

External barriers of the innate immune response are ____ and non specific

A

Immediate

29
Q

Immunity is the process where ___ is distinguished from ____

A

Self

Non self

30
Q

Once barriers have been breached by a pathogen, there must be a system to remove them once inside the body, describe the two methods used to identify foreign material in the body, how is this achieved?

A

Receptors that look for molecules/markers that are unique to pathogens (pattern recognition and lymphocytes antigen receptors)

An internal ID system that nearly all “self cells” carry

Accomplished by receptors in leukocytes and other immune cells that bind to pathogens or damaged tissue

31
Q

Phagocytic cells of the innate immune system are directly activated by molecules common to pathogens using

A

pattern recognition receptors

32
Q

True or false

There is only one type of pattern recognition receptors

A

FALSE

there are hundreds

33
Q

Where are pattern recognition receptors found

A

Host defence cells (mainly sentinel/look out cells) (macrophages, dendritic cells, mast cells)

Neutrophils

Come circulate as part of plasma protein

34
Q

What do cells with pattern recognition receptors do

A

Recognize (bind)

1) Basic components essential to pathogens (viral RNA, endotoxin of gram- bacteria)
2) molecules released from damaged tissue (heme)

35
Q

The molecules that cells with the pattern recognition receptors bind to are_____ so normal cells are not attacked by accident

A

Not present in mammalian bodies

36
Q

When pattern recognition receptors are activated or bound to, what does it stimulate

A

Inflammation
Anti parasitic activity
Initiates the adaptive immunity to create a memory

37
Q

True or false

Most cells of the mobile innate immune system are either sentinel or phagocytic

A

True

38
Q

What are sentinel cells

A

These are look out cells -alert the body of foreign material/bodies

Found at potential entry points

Activate immunity

Attract additional mobile defenders when needed

39
Q

What are come examples of tissue sentinel cells

A

Macrophages
Dendritic cells/dendritic macrophages
Mast cells

40
Q

Describe monocytes

A

Named for the single unit nucleus (Pleomorphic shape) (undivided)

Have pattern recognition receptors and antibody receptors

41
Q

What is the function of monocytes

A

Phagocytic (remove dying neutrophils and tissue)

Sentinel (release mediators (cytokines) that stimulate innate and adaptive immune response)

Migrate into tissues to become macrophages and dendritic cells

42
Q

Dead neutrophils are found most in areas of

A

Infection

43
Q

Describe the similarities and differences between macrophages and dendritic cells

A

Macrophages: derived from blood monocytes

Dendritic cells: derived from monocytes or lymphoid cells

Both are sentinel, phagocytic and found in tissues

Macrophages: stay in tissue and remove neutrophils and damaged tissue -stimulates innate immunity

Dendritic cells: reside in and move to lymph nodes after phagocytosing foreign material -stimulates adaptive immunity

44
Q

What are other names for neutrophils

A

Neutrophilic Granulocytes

Polymorphonuclear neutrophils (PMN) (deeply divided)

Band cells (immature) -nucleus is not divided)

45
Q

A lot of band cells indicates

A

A severe infection -the body is making neutrophils faster and they don’t have time to mature (not as effective) but are made in severe situations

46
Q

Neutrophils are one of the major WBCS: ___ %

A

40-75%

47
Q

Describe neutrophils

A 
Short life (days) 
Highly mobile

3 receptors:

1) patter recognition receptors for bacterial antigens -antigens common to microbes or damaged tissue (endotoxin)
2) antibodies (IgG) that have bound antigen
3) complement (blood Proteins activated by pathogens)

Mostly in blood
Rapidly migrate to inflammation sites

48
Q

What are the functions of neutrophils

A

Phagocytose bacteria and other small foreign particles

Destroy ingested material using enzymes (lysozyme) or generating peroxides

49
Q

Basophils (basophilic granules) are found in

A

Blood

These stain dark blue

50
Q

Describe mast cells

A

Found in tissue, NOT blood, often with eosinophils

Similar to basophils (common bone marrow precursor)

Some mast cells arise from bone marrow and mature in tissues

Other mast cells differentiate from blood basophils

Dominant cell in allergies and anaphylaxis (stimulate complete degranulation)

51
Q

What are the functions of basophils and mast cells

A

Sentinel

Activated by binding to: pattern recognition receptors or IgE

Release histamine and heparin from their granules when activated (increase blood flow in early inflammation)

52
Q

What is IgE

A

An antibody which binds strongly to basophils and mast cells, when it binds to its appropriate antigen it activates the cell

This is an example of cooperation between innate and adaptive immune system

53
Q

Describe eosinophils

A

Lobed nucleus with orange -red staining granules

Attracted by chemicals released from mast cells and pathogens

54
Q

What are the functions of eosinophils

A

Produce, stores in granules and release externally:

1) proteins which destroy nearby tissues
2) peroxides
3) enzymes including RNAase

Important in defence against allergies and parasitic infections

55
Q

Describe NK lymphocytes

A

Mononuclear

Circulate in blood and tissues (approx 20% of lymphocytes on a blood smear are NK)

Innate immune cells

These check to see if the cell is normal using an identification system

First responders to infection Known as MHC (first responders to viral attack in previously uninfected individuals)

56
Q

Viral infections take over the cell’s production system which means it no longer produces MHC, what does this mean for NK lymphocytes

A

NK lymphocytes are activated by the absence of MHC

57
Q

How to NK lymphocytes kill virus infected cells and tumour cells

A

Apoptosis (shutting down the cell)

Lyzing the cell

58
Q

Describe the complement system

A

A group of blood plasma proteins (and inflammatory fluid), some of which made in the liver or by macrophages, parts of the innate immunity, act as a bridge between the innate and adaptive immune system

Some of these proteins are enzymes that activate other complement proteins in a cascade type reaction (central protein C3)

59
Q

Describe the actions of the complement system

A

When activated, there is a variety of possible effects:

1) lysis of bacteria, cells and viruses
2) promotion of phagocytosis (opsonization) -this coats the pathogen to make phagocytes want it
3) triggers inflammation

60
Q

What are the 3 possible pathways/methods of activation of the complement system

A

The lectin pathway

The classical pathway

The alternate pathway

61
Q

What is the lectin pathway

A

Mannan-binding lectin

An acute phase reaction protein formed in the liver which binds to mannose sugars found on the surface of some pathogenic bacteria (this sugar is not found in mammalian cells) -this is an example of a soluble pattern recognition protein

When lectin is activated by binding, it triggers a cascade which then activates C3

62
Q

What is the classical pathway (most effective)

A

Occurs in late infections because antibody has to be produced

Activated by an antibody binding to its antigen (part of a pathogen)

This causes a shape change in the antibody molecule which activates the first complement protein C1

C1 is an enzyme then activate other complement proteins

Final stage is activation of C3

63
Q

What is the alternate pathway

A

C3 is an unstable protein that is constantly changing into its active form in plasma (spontaneous)

This is not a problem because healthy mammalian cell membranes inactivate C3

When C3 binds to bacterial cells, these have a different structure and C3 will continue to activate

64
Q

The activation of C3 by any of the 3 pathways results in the same four effects

A

1) Opsonization (C3 fragments bind to bacteria and macrophages/neutrophils have receptors that bind to these fragments which make it easier to phagocytize the bacteria)
2) fragments attract immune cells (mainly neutrophils)
3) some stimulate mast cells to degranulate (release histamine to make capillaries leaky which bring in protein and immune cells more easily)
4) Formation of the “membrane attack complex” which is a group of complement proteins that binds bacteria or viral cell walls

65
Q

What is interferon

A

A method of the innate immunity against viral infections

Produced by some dendritic cells, fibroblasts, and other cells

Rapid innate protection against viruses

66
Q

What does interferon do

A

These recognize viruses using pattern recognition receptors

It results in rapid production of interferon (immediate -minutes)

It acts locally on infected AND non infected cells

Changes the cells metabolism so that it is more difficult for viruses to function

Also Triggers the cell to destroy itself (programmed cell death)

67
Q

What is the significance of interferon

A

Interferon is used in therapy: recombinant feline interferon used to treat; dogs with parvovirus and cats with feline leukaemia virus (FeLV)

Some vaccines trigger interferon production (may give partial rapid protection while antibody levels build)

68
Q

Interferon is an example of a

A

Antiviral

Immunology (13 decks)

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