Microflora and Mucosal Immune System

Question 1

What are 3 GIT immune barriers?

Answer 1

Saliva, Epithelial barriers and the stomach

Question 2

Where are the highest numbers of microbes found in the GIT?

Answer 2

Colon

Question 3

What are 3 functions of microbial gut and give an example.

Answer 3

Metabolic functions - helps to produce short chain fatty acids
Protective functions - pathogen displacement
Structural functions - induction of lgA

Question 4

What are 2 types of lymphocytes?

Answer 4

T-cells (thymus)
B-cells (bone marrow)

Question 5

Where can B and T cells be found?

Answer 5

Distal Lymphoid aggregates eg. Peyers patches

Question 6

What protein is found on helper T lymphocytes?

Answer 6

CD4

Question 7

What protein is found on cytotoxic T lymphocytes?

Answer 7

CD8

Question 8

Which t helper cell responses predominate in the gut?

Answer 8

TH2

Question 9

What is the role of cytotoxic T cells?

Answer 9

Direct killing

Question 10

What is the role of TH1 cells?

Answer 10

Help macrophages

Question 11

What is the role of TH2 cells?

Answer 11

Help B cells
Activate B cells

Question 12

What are dendritic cells?

Answer 12

Antigen presenting cells in adaptive and innate response

Question 13

What is the role of phagocytes?

Answer 13

First responders to infection

Question 14

What is the role of epithelial cells?

Answer 14

barrier function facilitated by goblet cells

Question 15

What do goblet cells secrete?

Answer 15

Mucins
Lysozyme

Question 16

What do Paneth cells secrete?

Answer 16

Defensins granules
lgA
crypts of Lieberkühn

Question 17

What is immune tolerance?

Answer 17

Tolerance to microbiota by M cells

Question 18

What is oral tolerance?

Answer 18

Tolerance to ingested soluble antigens by dendritic cells

Question 19

Where are M cells found?

Answer 19

Gut associated lymphoid tissue
Interspersed between enterocytes
Close contact with subepithelial lymphocytes and dendritic cells

Question 20

What is a feature of M cells?

Answer 20

Basolateral membrane is invaginated and contains T cells, B cells and macrophages

Question 21

What is the function of M cells?

Answer 21

Take up antigens from gut lumen by endocytosis

Question 22

Where are NOD like receptors found?

Answer 22

Cytoplasm

Question 23

What do NOD like receptors recognise?

Answer 23

PAMPs

Question 24

What do NOD like receptors activate?

Answer 24

Intracellular signaling cascade via NFKappaB or Capase

Question 25

What are NOD2 polymorphism linked to?

Answer 25

Bowel disease

Question 26

Where are TLRs found?

Answer 26

Plasma and endosome membrane

Question 27

What are TLRs associated with?

Answer 27

Innate immune response (pro-inflammatory)

Question 28

What does Inflammatory Bowel Disease result from?

Answer 28

Inappropriate inflammatory response to intestinal microbes in a genetically susceptible host

Question 29

What does Crohn's disease affect?

Answer 29

Any part of GIT Skio lesions

Question 30

What does Ulcerative colitis affect?

Answer 30

Colon

Question 31

What is C.difficile Colitis?

Answer 31

Over colonization by C.diff (lack of pathogen displacement by commensal bacteria) Causes toxic release and cell death