Mucosal Immunity Flashcards
2 examples of organised lymphoid structures in mucosal immune system
Peyer patches
Isolated lymphoid tissues
What do lymphoid tissues contain
Memory B cells, locally homed T cells, IgA antibodies, regulatory T cells and distinctive microbiota
Name the 4 different types of cells which make up the endothelium after differentiation from stem cells
Enterocytes
Paneth cells
Goblet cells
Enteroendocrine cells
Why is it that the presence of IgA in the gut lumen does not cause inflammatory response
It does not activate complement
How is IgA, secreted by B cells, transported to the apical face of the endothelium
Endocytosis through epithelia
Name the two types of intraepihelial lymphocytes (IELs)
Type A- Cd8+ T cells
Type B- respond to cells under stress expressing mic-A and mic-B
What sort of cells sample the gut lumen contents
Intestinal epithelial cells (IECs)
Describe 3 ways that DCs obtain information about the surroundings from enterocytes
Non-specific transfer of contents through the enterocytes
Fc-Rn dependant transport
Apoptosis dependent transfer
Antigen capture
What is the name of the specific type of dendritic cells which sample the mucosa
CD103+
What is the roll of CD103+ DCs when they detect infection
Generate Treg cells
Home t and B cells to infected area via MADCAM ligands
How do commensal bacteria inhibit with pathogens
They outcompete them for the pathways required for uptake
How is physiological inflammation achieved and what is the point of it
It occurs from interaction with commensal bacteria resulting in the down regulation of inflammatory pathway
How is infection first recognised and what are the immediate effects
By tlrs or nods which activate NFkB causing epithelial cells to produce inflammatory cytokines, chemokines and other mediators
Which cells are initially recruited to the site of infection in response to cytokines and chemokines produced by epithelial cells
Neutrophils, macrophages and dendritic cells
How does shigella toxin enable invasion
It inhibits translation
How does clostridium dificile toxin A enable invasion
It inhibits GTPase activity
How does the retrovirus toxin NSP4 enable invasion
It disrupts tight junctions
What does TH-2 produce upon Helminth infection in order to repair epithelial cells
IL-13
Which cytokines are produced by th2 in response to Helminth infection in order to recruit and activate macrophages
IL-4 and Il-13
What does the production of IL-4 from th2 cells induce B cells to do
Produce IgE
What does the production of il-5 from th2 cells stimulate
Activation and recruitment of eosinophils
Which interleukins secreted by th2 drive mast cell recruitment?
Il-9 and IL-3
What do mast cells produce to recruit inflammatory cells and remodel mucosa
Histamine, TNFa and MMCP
What do eosinophils produce to kill parasites
MBP
What are the characteristics of mucosal surfaces
Thin and permeable
