Lecture 4 - Innate Immunity

Question 1

What is infectivity?

Answer 1

The ability for a microorganism to infect a host and therefore establish itself

Question 2

What is virulence?

Answer 2

The ability of a microbe to drive/cause tissue damage

Question 3

Which 3 groups of people have weak immune systems and are therefore more susceptible to infections?

Answer 3

Elderly people (65yrs +)
Children (less than 5 yrs)
Pregnant women

Question 4

What is the definition of the immune system?

Answer 4

The cells and organs that contribute to immune defences against infectious and non-infectious conditions

Question 5

What is an infectious disease?

Answer 5

When the pathogen succeeds in evading and/or overwhelming the hosts immune defences

Question 6

What are the roles of the immune system?

Answer 6

Pathogen recognition
Containing/eliminating the infection
Regulating itself (ending once infection is gone)
Remembering pathogens (immunological memory)

Question 7

What principles do vaccines use to work?

Answer 7

Modified version of microbe
Stimulates normal immune response from body
Immunological memory created (preventing illness when infected by actual pathogen)

Question 8

What are the 2 components to the immune response?

Answer 8

Innate immunity
Adaptive immunity

Question 9

What is the main difference between innate and adaptive immunity?

Answer 9

Innate immunity provides immediate protection
Adaptive immunity provides long lasting protection

Question 10

What are the features of the innate immunity giving immediate protection?

Answer 10

Fast/rapid acting
Lack of specificity
Lack of memory
No change in intensity

Question 11

What are the feature of the adaptive long lasting protection ?

Answer 11

Slow
Specific
immunological memory
Changes in intensity (due to immunological memory, faster and stronger upon repeat infection)

Question 12

In innate immunity, what are the 4 first lines of defence?

Answer 12

Physical barriers
Physiological barriers
Chemical barriers
Biological barriers

Question 13

What is the general function of the first lines of defences in innate immunity?

Answer 13

They prevent the entry and limit the growth of pathogens

Prevent microbes getting in

Question 14

What are the innate physical barriers to infection?

Answer 14

Skin
Mucous membranes
Bronchial cilia

Question 15

Where are the mucous membranes of the body located?

Answer 15

Mouth
Respiratory tract
GI tract
Urinary tract

Question 16

What is the function of the Bronchial cilia?

Answer 16

Waft mucus that has trapped pathogens to the back of the oesophagus to be swallowed and destroyed

Question 17

What are the physiological barriers of innate immunity?

Answer 17

Diarrhoea
Vomiting
Coughing
Sneezing

These usually happen once a pathogen has breached a physiological barrier

Question 18

What is the general function of the physiological barriers?

Answer 18

Usually trying to expel pathogens from the body

Question 19

What are the chemical barriers of innate immunity?

Answer 19

Low pH (skin, stomach and vagina)
Antimicrobial molecules:
-(IgA in saliva, tears and mucous membranes)
-Lysozymes
-Mucus
-Beta-defensins
-Gastric acid + pepsin

Question 20

What are Beta-defensins?

Answer 20

Chemicals with antimicrobial properties

Question 21

How does IgA (Immunoglobulin A) act as an antimicrobial molecule?

Answer 21

Prevent attachment to host

Antibody that binds to microbe preventing it attaching to the host

Question 22

What is the biological barrier of the body?

Answer 22

The normal flora of the body

Question 23

What is meant by the normal flora of the body?

Answer 23

Non pathogenic microbes that are normally present in/on the body

Can cause disease when displaced from intended site

Question 24

Where is the normal flora of the body normally located?

Answer 24

Skin
All mucosal surfaces

Question 25

How does the bodies normal flora act as a biological barrier to infection?

Answer 25

Competition Competes with pathogens for attachment sites and resources Produce antimicrobial chemicals

Question 26

Which organ in the body deals with encapsulated bacteria?

Answer 26

Spleen

Question 27

Where is Staphylococcus aureus normally found and what condition does it cause if it invades the body?

Answer 27

Skin Invades subcutaneous layer causing: CELLULITIS

Question 28

Where is Streptococcus pyogenes normally found and what disease does it cause if it is displaced?

Answer 28

Skin Scarlet fever

Question 29

Where is Streptococcus mutans normally found and what disease can it cause if its displaced?

Answer 29

Mouth and nasopharynx Endocarditis

Question 30

Where is E.coli normally found and what disease does it cause if its displaced?

Answer 30

GI tract Food poisoning

Question 31

How can the normal flora be displaced from its normal location?

Answer 31

Breaching the skin integrity Fecal oral route Fecal-perineal-urethral route (UTIs women)

Question 32

Where is the main portal of entry for microbes into the body?

Answer 32

The mouth

Question 33

When do problems with normal flora arise?

Answer 33

Normal flora displaced Overgrowth when host is immunocompromised Normal flora depleted due to antibiotics

Question 34

How does Chemotherpy cause problems with the normal flor?

Answer 34

Inflames the mucous membranes (mucositis) allowing normal flora to invade the host

Question 35

What are the secondary lines of defence in innate immunity that lead to Inflamation?

Answer 35

Phagocytes Chemicals

Question 36

What is the function of the secondary line of defence of innate immunity?

Answer 36

They contain and clear the infection

Question 37

What are exogenous microbe invaders?

Answer 37

Microbes that invade that aren’t normally present in the host

Question 38

What are endogenous microbe invaders?

Answer 38

Normal flora that breach and invade

Question 39

What are phagocytes?

Answer 39

White blood cells which first respond to an infection and engulf a pathogen

Question 40

What are the 3 types of phagocyte?

Answer 40

Macrophage Monocytes Neutrophils

Question 41

What is a macrophage?

Answer 41

Phagocyte only found in tissues and organs

Question 42

What is the function of a macrophage?

Answer 42

Phagocytosis (ingest and destroy microbes) Present antigens to T cells (adaptive immunity) Make cytokines/chemokines

Question 43

What important clinical marker do cytokines cause elevated levels of?

Answer 43

cRP (c Reactive Protein)

Question 44

What are monocytes?

Answer 44

Phagocytes found in the blood They migrate to tissues and differentiate into macrophages

Question 45

How are neutrophils different to macrophages?

Answer 45

Neutrophils = Increased levels during infection + Shorter lived than macrophages

Question 46

What are the functions of basophils/mast cells?

Answer 46

Inflammation (histamines) Allergic reactions

Question 47

What is the function of eosinophils?

Answer 47

Defence against parasites (multicellular)

Question 48

What is the function of natural killer cells?

Answer 48

Kill all abnormal host cells

Question 49

What is the function of dendritic cells?

Answer 49

Present microbial antigens to T cells (important for acquired immunity)

Question 50

How do phagocytes recognise which microbes are pathogens to be ingested?

Answer 50

PAMPs PRRs

Question 51

Where are PAMPs located? What does it stand for?

Answer 51

On microbes/pathogens Pathogen Associated Molecular Patterns

Question 52

Where are PRRs located? What does it stand for?

Answer 52

On phagocyte Pathogen Recognition Receptors

Question 53

How do PAMPs of microbes interact with the PRRs of phagocytes?

Answer 53

The phagocytes PRRs (Pathogen Recognition Receptors) will match the PAMPs (Pathogen-associate molecular patterns) on the pathogen

Question 54

How is it useful for 1 PRR on a phagocyte to match/recognise multiple PAMPs?

Answer 54

Phagocyte can recognise and phagocytose many different pathogens

Question 55

What is opsonisation of microbes?

Answer 55

When the host coats microbes in proteins (opsonise) which a phagocyte can recognise leading to enhanced attachement to phagocytes

Question 56

What can act as opsonins?

Answer 56

Complement proteins (C3b) Antibodies (IgM and IgG) Acute phase proteins (C-reactive protein cRP)

Question 57

If opsonins are not present or non functional, which type of microbes cant be removed?

Answer 57

Encapsulated bacteria: -Neisseria meningitidis -Haemophilus influenzae -Streptococcus pneumoniae

Question 58

How does phagocytosis take place?

Answer 58

Pathogen recognised Pathogen binds to phagocyte Engulfed Phagosome Phagolysosome Digested

Question 59

How does a phagocyte kill a microbe once its been engulfed in a phagolysosome? (Main mechanism)

Answer 59

Respiratory burst/ Oxygen-dependant pathway

Question 60

What is involved in the chemical portion of the second line of defence of innate immunity?

Answer 60

Complement system/proteins Cytokines

Question 61

What is the complement system? What organ is the main contributor to producing complement?

Answer 61

Proteins in blood serum which get activated by coming into contact with invading microbes Liver = main complement producing organ

Question 62

Which complement proteins attract phagocytes to microbes? (Chemoattractants)

Answer 62

C3a C5a *

Question 63

Which complement protein binds to pathogens (opsonisation)?

Answer 63

C3b

Question 64

Which complement proteins bind to surface of pathogens and kill the pathogen?

Answer 64

C5 C6 C7 C8 C9

Question 65

What is the function of cytokines?

Answer 65

Chemoattraction Activates phagocytes Inflammation

Question 66

What systemic affects do cytokines have ini the body?

Answer 66

Liver makes opsonins Bone marrow mobilises neutrophils Fever (hypothalamus increases body temp)

Question 67

How do cytokines cause local inflammation?

Answer 67

Vasodilation Increased vascular permeability

Question 68

Innate immune response summarised:

Answer 68

Innate barrier may get breached Complement proteins made/activated Macrophages/phagocytes activated Cytokines made Vasodilation/vascular permeability Chemoattraction Fever Inflammation

Question 69

When may phagocytosis be reduced causing problems?

Answer 69

Asplenic/Hyposplenic patients Neutropenia (chemotherapy, leukaemia, certain drugs) Decreased neutrophil function (Chronic Granulomatous Disease caused by NAPDH oxidase defect)

Question 70

Give 2 conditions where neutrophils have decreased function:

Answer 70

Chronic granulomatous disease (no respiratory burst) due to phagocyte NADPH oxidase deficiency Chediak-Higashi syndrome (No phagolysosome formation)

Question 71

First line defences and second line defences of innate immunity purpose:

Answer 71

First line = limit entry and growth of pathogens at portals of entry Second line = contain and eliminate infection

Question 72

What specific cytokines produced by macrophages stimulate the liver to produce CRP?

Answer 72

IL-1 IL-6 TNF-a (Tumour Necrosis Factor - Alpha))

Question 73

What is the function of cRP? What stimulates its production?

Answer 73

Opsonisation Macrophages producing the cytokines IL-1, IL-6 and TNF-a

Question 74

What cells produce IL-1, IL-6 and TNF-a? What do these cytokines do?

Answer 74

Macrophages produce them These cytokines are pyrogens inducing fever