026 Tissue Immune responses Flashcards
Describe mucosal immunity in the gut?
M cells will detect antigens and endocytose them into the subepithelial dome, in which it will bind to dendritic cells. Dendritic cells will present this to T and B cells in the T cell area or the follicles respectively. T and B cells will migrate to the local mesenteric lymph nodes and undergo differentiation. They will then pass into the blood stream via the thoracic duct and home to the efferent lamina propria. IgA formes to protect the intestine.
How does cell homing work?
Addressins in the capillaries (MadCAM-1) will detect the integrin on the lymphocytes. It causes lymphocyte to slow down and enter the tissues.
Describe the transport of IgA molecules from the submucosa to the lumen?
IgA in the submucosa is dimeric, held by a J protein. It binds to poly Ig receptor on the basal membrane of the epithelial cells. This binds to the J chain and endocytose the IgA in vesicles through the intestinal cell to the apical site, where it is cleaved. A small part of the poly ig receptor is bound to the J chain, acting as the secretory component, preventing degradation.
How do haptens cause delayed type sensitivity?
Haptens bind to the keratinocytes, mutating it to become foreign. This causes a huge secondary immune response when exposed to it again. E.g. PPD hair dye
What are defensins, and which types are located where?
These punch holes in the cells. Skin - Beta defensins Gut & lung - alpha defensins
Describe the release of granules in mast cells causing inflammatory response?
The Fc region of IgE is bound to FceRN receptos on mast cells. When the Fab region is stimulated it causes mast cell to release inflammatory factors causing vasodilation, recruitment of eosinophils and neutrophils etc.
What is the lamina propria?
This is the effector site in which the specialised T and B cells induced by the peyers patch is released.
How does maternal milk IgG get transferred to babies?
Babies have FcRN receptors on the apical and basal sites of their enterocytes. When it encounters IgG, it will attach to the FcRN of IgG under acidic conditions. This will endocytose IgG to the basal lateral side, where it is released due to the increase in pH.
What are hepatic sinusoids?
These are where immune
Which immune responses are found in the hepatic sinusoids?
Kupffer cells, Pit cells, Dendritic cells.
How does the GI tract provide a tolergenic environment?
There are intraepithelial Treg cells that mediate tolerance . Gut microbiota also assist.
Which cells/cytokines are released by liver to provide its tolergenic environment?
IL10, Treg, TNFB
What is the basis of vaccination strategy?
That immunisation protection in one mucosal surface will lead to the same protection on another surface
