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Immunology > 3.2 Mucosal immunity > Flashcards

3.2 Mucosal immunity Flashcards

1
Q

___ and ____ are susceptible to infection

A

External surfaces
Skin ( stratified squamous, thick layers, good for defense)

Mucous membranes: are particularly more due susceptible (easily infected) since they are thin Walled to allow physiological function
-respiratory tract: gaseous exchange
- GIT: absorption of nutrients

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2
Q

Innate immunity at mucosal sites:

A
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3
Q

Protect the respiratory epithelium:

A

Mucociliary escalator and alveolar macrophages

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4
Q

Alveolar =

A

Gaseous exchange

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5
Q

In milk-fed animals
e.g. calves, the GIT is colonised by

A

lactobacilli that produce lactic and butyric acid which have antimicrobial properties

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6
Q

Treatment of rabbits with penicillin can lead to?

A

fatal enterotoxaemia - can wipe out microbiome allowing gut to repopulate with bad species like clostridium

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7
Q

Gamma:delta T cells are found where?

A

Found beneath enteric mucosal epithelium

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8
Q

Gamma: delta T cells

A

Invariant receptors
– unlike conventional αβ T cells

Do not require MHC
– recognise stress proteins / symptoms

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9
Q

Gamma delta (gd) T cells are important for innate protection of mucosa in

A

in farm animals (90% of T cells in pigs are gd)

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10
Q

Mucosal-associated lymphoid tissues (MALT): ( common mucosal system)

A

– Tonsils
– Peyers patches
– Mesenteric lymph nodes
– Bronchial-associated lymphoid tissue
– Mammary gland lymphoid tissue

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11
Q

Antigen stimulation at one site leads to

A

recruitment and response in ALL mucosal lymphoid tissue.

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12
Q

Adaptive immunity: Antigen delivered via non-mucosal route

A

Ex: vaccine given SQ or IM
– IgM and IgG antibodies predominate
– Systemic protection from infection

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13
Q

Antigen delivered via mucosal route

A

– IgA and IgE antibodies predominate
– Mucosal protection from infection

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14
Q

Antigen exposure in the gut is usually recognised by

A

cells in Peyer’s patches in the ileum

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15
Q

Antigen exposure in the gut is usually recognised by

A

by cells in Peyer’s patches in the ileum

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16
Q

microfold (M) cells:

A

Specialised epithelial cells that sample luminal contents and transport antigen to underlying lymphoid tissue

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17
Q

M cell process:

A
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18
Q

Adaptive immunity in MALT: B cell response

A

– Mainly IgA production
– IgE production important against parasites
– Some IgG in case of systemic spread of infection

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19
Q

Adaptive immunity in MALT: T cell response

A

Mainly T helper type 2 (TH2) and TH3 cells
- TH2 > IL-4: stimulates B cell class-switching to IgE
- TH3 > TGF-beta: stimulates B cell class switching to IgA

20
Q

IgA is produced by

A

plasma cells in submucosa and is transported by epithelial cells into lumen

21
Q

IgA functions:

A

NEUTRALISING antibody on the mucosal surface
- Viruses
- Bacterial adhesins
- Microbial toxins

22
Q

IgA protects against

A

infection (neutralisation)

23
Q

___ and ___ are effective if epithelial barrier is breached

A

IgE and IgG

24
Q

IgE allows

A

submucosal mast cells and eosinophils to detect and expel helmith parasites

25
Q

Problem with IgE

A

can lead to dietary hypersensitivity

26
Q

The main function of the GIT is?

A

Absorption of nutrients

27
Q

The MALT must be able to

A

distinguish food antigens from pathogen antigens

28
Q

Dietary proteins do not express

A

PAMPs:
– Initial activation which is inhibited following generation of regulatory T cells producing immunosuppressive cytokines
- mucosal tolerance

Exposure to pathogens leads to innate respond and inflammation in the GIT
– PRR detection of PAMPs by cells of innate immunity
– Pro-inflammatory cytokines amplify adaptive response

29
Q

“sample” the liminal contents for mucosal tolerance

A

Dendritic cells

30
Q

Mucosal tolerance: Harmless antigens

A

Produces immunosuppressive cytokines to switch off the immune response

31
Q

Gluten-sensitive enteropathy (Coeliac disease)

A

• Dietary allergy to gluten
• Irish setter dogs
• Feed a gluten-free diet

32
Q

Migration of B cells from the MALT to the mammary gland and secretion of antibodies is important for neonatal immunity:

A
  • Neonatal immune system is poorly developed
  • Mucosal surfaces of newborn animals are particularly vulnerable to infection
  • Passive transfer of maternal antibody in colostrum & milk protects neonates from pathogens
33
Q

Farm animal species rely on transfer of antibodies in

A

Colostrum and milk

34
Q

Colostrum is rich in

A

IgG

35
Q

Milk contains predominantly

A

IgA (mucosal protection)

36
Q

IgG in colostrum is important for

A

systemic protection of the neonate

37
Q

IgA in milk is important for

A

mucosal protection of the neonate

38
Q

Absorption of colostrum

A
  • Colostrum IgG binds to specialised Fc receptors expressed on intestinal epithelial cells of neonates (FcRn).
  • Antibodies are actively taken up and passed into lacteals and then on to blood.
39
Q

Absorption of colostrum : how long is this process active?

A

This process is only active for the first 24 hrs after birth (most absorption in first 6-12 hrs)

40
Q

Maternally-derived antibodies (MDA) provide protection for how long?

A

~12 weeks. Can interfere with vaccination

41
Q

Antibodies in milk;

A
  • No longer any systemic absorption of antibodies
  • But milk contains IgA which continues to protect the GIT of the neonate from enteric pathogens
42
Q

Failure of Passive Transfer (FPT) =

A

Insufficient or poor quality colostrum produced by mother
– Premature birth
– Nutritional deficiencies

Inadequate intake by newborn

43
Q

Why is FPT a major concern in foals

A
  • Foals need at least 400 mg/dL serum IgG
  • Foals are susceptible to infection
44
Q

Diagnosis of FPT:

A

Blood test ~12 hours of age

45
Q

Treatment of FPT

A

If tested < 400 mg/dL and foal less than 18 hours old – Administer oral colostrum to ‘top up’

If tested < 200 mg/dL and foal more than 18 hours old
– Can administer IV plasma infusion

46
Q

Neonatal isoerythrolysis:

A

Stallion and mare have incompatible blood types:
- Foal inherits sire’s RBC antigens
- Mare makes antibodies to foetal RBCs
- Foal is born and suckles, absorbing IgG into
the circulation
- Maternal antibodies attack foals RBC’s
- Anaemia and jaundice result

Immunology (10 decks)

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