Mucosal Immunology Flashcards
What is the systemic immune system?
Bone marrow, spleen, thymus, lymph system and blood circulation
What is the mucosal system comprised of?
Eyes, nose, mouth, lungs, gut, Genitourinary tract
What is the main route for infectious microorganisms?
Mucosal immune system
What are the two mechanisms within the mucosal immune system?
Innate and adaptive
What are the innate mechanisms within the mucosal immune system?
Mucin, peristalsis, antimicrobial peptides and proteins
What must the adaptive mechanisms within the mucosal immune system differentiate between?
Harmful pathogens and harmless antigens- foods and commensal bacteria
What is in the mucosal barrier?
Secretory IgA/ IgM and a bit of IgG
What are the two sources of saliva?
Salivary glands and gum/teeth barrier
How is saliva made at the gum epithelium and whys it special?
Epithelium gets really thin where it meets the tooth so fluid from the blood leaks into mouth- no cells only serum components
What are intra-epithelial lymphocytes?
Lymphocytes that are squeezing out of the epithelium
What are the three types of lymphoid cells in the gut?
Intra-epithelial lymphocytes, lymphocytes and macrophages, Peyers patches
Where are the lymphocytes and macrophages found in the gut?
Lamina proprietor
What can dendritic cells do in the gut?
Extend their dendrite through the epithelial layer and sample what’s going on in the lumen
What are peyers patches similar in structure and function to?
Lymph nodes
What are peyers patches full of?
Lymphocytes
What’s the structure of peyers patches?
Different types of lymphocytes in different areas of the peyers patch- has columnar epithelium and forms a dome shape. The epithelium is interspersed with M cells
Where do M cells lie?
Slightly below epithelial cells
What type of cell are M cells?
Antigen presenting cell
What are the surface of M cells like?
Have microfolds
What are M cells invaginated by?
Lymphocytes
What do M cells do?
Take tiny samples of GI fluid
What are taken up by M cells?
Viruses, particles and macromolecules, parasites and bacteria
What happens if a lymphocyte is activated in a peyers patch?
Proliferates and moves out of the peyers patch into the lymph drainage system
What happens after lymphocytes from the peyers patch move into the lymph drainage system?
They go to the mesenteric lymph node where they mature and move into bloodstream- they hone into the small intestine but also all the way along the GIT
What is the common mucosal immune system?
Lymphocytes from one area of the GIT will spread evenly along all the mucosal sites
What are the main type of mucosal antibodies?
SIgA
What is SIgA found in?
All secretions and breast milk
What benefits do SIgA give to newborn infants?
Passive immune protection
Why do secretory antibodies survive better than the serum antibodies in the gut?
The secretory component protects it from the protease enzymes in the gut
What are the main structural differences between secretory and serum antibodies?
Secretory are dimerised, with a joining component and secretory component connecting them, serum are singular
What does aggregation mean for bacteria?
Harder to get through the mucosal surface in big groups
What gives IgA1 antibodies flexibility?
The hinge region
What are the 4 functions of SIgA?
Immune exclusion, intra-cellular neutralisation, virus excretion, interactions with non-specific factors (lysozyme, lactoferrin, peroxidase)
What are the 6 approaches to oral immunisation?
- Attenuated virus
- attenuated recombinant bacterial mutants
- mucosal adjuvants
- liposomes, microspheres
- capsules
- transgenic edible plants
What is the difference between mucosal secondary immune response and systemic secondary immune response?
Much smaller and antibodies disappear quite quickly
What are the steps in creating an oral vaccine from GM plants?
- hep B surface antigen gene transferred from yeast into a plant cell
- potato plants are regenerated from transformed cells
- hep B vaccine is correctly expressed by potato plants
- GM potatoes are harvested containing the hep B vaccine
What is oral tolerance?
If an antigen is first encountered through the mucosal immune system, the systemic immune system may become unresponsive to the antigen
Why is oral tolerance a thing?
Prevents immune reactions to all food
