Microflora and Mucosal Immune System Flashcards
What are 3 GIT immune barriers?
Saliva, Epithelial barriers and the stomach
Where are the highest numbers of microbes found in the GIT?
Colon
What are 3 functions of microbial gut and give an example.
Metabolic functions - helps to produce short chain fatty acids
Protective functions - pathogen displacement
Structural functions - induction of lgA
What are 2 types of lymphocytes?
T-cells (thymus)
B-cells (bone marrow)
Where can B and T cells be found?
Distal Lymphoid aggregates eg. Peyers patches
What protein is found on helper T lymphocytes?
CD4
What protein is found on cytotoxic T lymphocytes?
CD8
Which t helper cell responses predominate in the gut?
TH2
What is the role of cytotoxic T cells?
Direct killing
What is the role of TH1 cells?
Help macrophages
What is the role of TH2 cells?
Help B cells
Activate B cells
What are dendritic cells?
Antigen presenting cells in adaptive and innate response
What is the role of phagocytes?
First responders to infection
What is the role of epithelial cells?
barrier function facilitated by goblet cells
What do goblet cells secrete?
Mucins
Lysozyme
What do Paneth cells secrete?
Defensins granules
lgA
crypts of Lieberkühn
What is immune tolerance?
Tolerance to microbiota by M cells
What is oral tolerance?
Tolerance to ingested soluble antigens by dendritic cells
Where are M cells found?
Gut associated lymphoid tissue
Interspersed between enterocytes
Close contact with subepithelial lymphocytes and dendritic cells
What is a feature of M cells?
Basolateral membrane is invaginated and contains T cells, B cells and macrophages
What is the function of M cells?
Take up antigens from gut lumen by endocytosis
Where are NOD like receptors found?
Cytoplasm
What do NOD like receptors recognise?
PAMPs
What do NOD like receptors activate?
Intracellular signaling cascade via NFKappaB or Capase
What are NOD2 polymorphism linked to?
Bowel disease
Where are TLRs found?
Plasma and endosome membrane
What are TLRs associated with?
Innate immune response (pro-inflammatory)
What does Inflammatory Bowel Disease result from?
Inappropriate inflammatory response to intestinal microbes in a genetically susceptible host
What does Crohn’s disease affect?
Any part of GIT
Skio lesions
What does Ulcerative colitis affect?
Colon
What is C.difficile Colitis?
Over colonization by C.diff (lack of pathogen displacement by commensal bacteria)
Causes toxic release and cell death
