Oral Mucosal Immunity

Question 1

Name 4 challenges of the mucosal surfaces

Answer 1

1. Most frequent point of entry for pathogens so must have effective response
2. Must tolerate commensal organisms
3. Oral cavity membranes must protect and tolerate environmental insults
4. GIT membranes must allow absorption of nutrients

Question 2

What 2 bacteria colonise the oral cavity in the birth canal?

Answer 2

1. Lactobacilli

2. Bacteroides

Question 3

When are reservoir populations established in the tongue and mucosa?

Answer 3

During infancy

Question 4

What 3 things can alter the colonisation of the oral cavity?

Answer 4

1. Tooth eruption
2. Hormonal shifts
3. Complete loss of teeth

Question 5

What is the function of junctional epithelium?

Answer 5

Helps gum tissue to join to tooth

Question 6

Where is particularly susceptible for microorganisms to enter in the oral cavity?

Answer 6

Junctional epithelium

Question 7

What characterises oral mucosa in contrast to skin?

Answer 7

1. Highly vascularised

2. Highly permeable

Question 8

What is MALT?

Answer 8

Mucosa-associated l

Question 9

What initiates immune responses to antigens along mucosal surfaces?

Answer 9

Mucosal immune system (MALT)

Question 10

What are MALT inductive sites?

Answer 10

Secondary immune tissues where antigen sampling occurs and immune responses are initiated

Question 11

What are MALT effector sites?

Answer 11

Sites at which effector cells perform their function

Question 12

Name an example of a MALT effector site

Answer 12

Sites of IgA transport across the mucosal epithelium

Question 13

What regulates mucosal immunity?

Answer 13

Coordination between inductive and effector sites

Question 14

What glands are examples of inductive and effector sites?

Answer 14

Salivary

Question 15

Where are mucosal dendritic cells found?

Answer 15

Oral mucosa inductive site

Question 16

What is the function of mucosal dendritic cells?

Answer 16

Capture and present antigens found in the oral cavity

Question 17

How do mucosal dendritic cells present antigens?

Answer 17

Capture antigens from peripheral tissues and migrate to lymph nodes through lymphatic vessels

Question 18

What type of epithelium is found in the soft tissues of the human oral cavity?

Answer 18

Stratified squamous epithelium

Question 19

What 2 areas of the oral cavity have keratinised epithelium?

Answer 19

1. Gingiva

2. Hard palate

Question 20

What 3 areas of the oral cavity have non keratinised epithelium?

Answer 20

1. Floor of the mouth
2. Buccal regions
3. Soft palate

Question 21

What mucosa is found in the GIT?

Answer 21

Simple epithelium

Question 22

Why are epithelial cells shed continuously?

Answer 22

Form a protective shield against pathogens

Question 23

What is the function of keratinised epithelium?

Answer 23

Mechanical barrier which makes this epithelium more resistant to wear and injury

Question 24

Name 5 functions of saliva

Answer 24

1. Maintains homeostasis of oral environment
2. Maintains moist atmosphere
3. Maintains stable, slightly acidic, pH
4. Flush microorganisms from mucosal and tooth surfaces
5. Mucins lubricate surfaces

Question 25

What happens to pathogens flushed from mucosal and tooth surfaces by saliva?

Answer 25

Swallowed and inactivated in the stomach

Question 26

Name 2 major antimicrobial components of saliva

Answer 26

1. Lactoferrin | 2. Salivary peptides

Question 27

What are 2 functions of lactoferrin?

Answer 27

1. Binds iron, leading to bacterial growth inhibition, particularly in gram negative anaerobes 2. Inhibits colonisation of oral bacteria and dental plaque formation

Question 28

Name 2 salivary peptides

Answer 28

1. Histatins | 2. Defensins

Question 29

What are histatins?

Answer 29

Small salivary-derived histidine rich polypeptides with marked antifungal activity

Question 30

Name 3 salivary enzymes

Answer 30

1. Lactoperoxidase 2. Lysozyme 3. IgA

Question 31

What is the function of lactoperoxidase?

Answer 31

Catalyses formation of hypothiocyanite ion from hydrogen peroxide and thiocyanate ion, which reacts with sulfhydryl groups in proteins and inhibits bacterial metabolism

Question 32

What is the function of lysozyme?

Answer 32

Acts on peptidoglycans in the cell wall of susceptible bacteria causing cell lysis and death

Question 33

Name 3 functions of secretory IgA

Answer 33

1. Prevents bacterial adhesion to host cells or salivary pellicle 2. Acts as specific agglutinin of bacteria and fungi 3. Has anti-inflammatory properties

Question 34

What is salivary pellicle?

Answer 34

Layer of saliva which forms over tooth

Question 35

What are IgA's anti-inflammatory properties?

Answer 35

Binding of IgA to Fc-a receptors on macrophages and PMNs downregulates pro-inflammatory cytokine production

Question 36

Name 3 characteristics of secretory IgA

Answer 36

1. Found as dimer connected by J chain 2. Contains secretory component ("Sc" protein) 3. Secreted by plasma cells in salivary glands

Question 37

What is gingival crevicular fluid?

Answer 37

A serum transudate or inflammatory exudate derived from periodontal tissues and found in the gingival sulcus

Question 38

Name 3 places from where the components of GCF are derived

Answer 38

1. Serum 2. Periodontal tissues 3. Bacteria

Question 39

Name 3 protective functions of GCF

Answer 39

1. Flow washes away bacteria and toxic by-products 2. Immunoglobulins bind to bacteria and opsonise them 3. Enzymes released within GCF destroy bacteria and bacterial products

Question 40

What are the 2 main sources of immunoglobulins in the oral cavity?

Answer 40

1. Salivary glands | 2. Mucosal plasma cells

Question 41

What cells are of particular importance in defending the gingival crevice?

Answer 41

Neutrophils

Question 42

What is the main function of the unique defensive properties of the oral cavity?

Answer 42

Protect teeth, jaws, gingival and oral mucosal tissues against infection

Question 43

Name 2 things which can affect the balance of microbial flora in the oral mucosa

Answer 43

1. Broad spectrum antibiotics | 2. Immunocompromising diseases

Question 44

What 5 things can allow bacteria to avoid destruction in the oral cavity?

Answer 44

1. Production of bacterial proteases which degrade immunoglobulin and complement molecules 2. Production of exotoxins which alter immune and inflammatory cell function 3. Development of complex oral bacterial eco-systems biofilms 4. Bacteria are difficult to detect following invasion of epithelial cells 5. Crypts and fissures of the tongue are favourable for gram negative anaerobes

Question 45

Why does a biofilm tend to protect bacteria?

Answer 45

Many of the bacterial antigens are hidden in the biofilm