T1 L11: Mucosal immunology 2 Flashcards
What role do immune cells in liver sinuses have?
They maintain tolerance and protect us from microbes in the portal vein
What are the 2 subtypes of intraepithelial lymphocytes (IEL)?
-Tissue-resident memory T-cells
Eg. TCRαβ+CD8αβ+
-Innate-like and innate lymphocytes
Eg. mucosa-associated invariant T-cell cells (MAIT), Nk-T-cell, NK-cells
What is the function of Perforin Granzyme Fas?
It allows for the apoptosis pathway when cells are infected by viruses
What is the function of Perforin Granzyme?
It allows for the apoptosis pathway in the presence of toxic peptides
How do Treg cells help to maintain tolerance?
They are produced in response of harmless commensals in the presence of retinoic acid
They produce IL-10 and other cytokines which maintain tolerance to commensals and food
What is meant by immune exclusion?
Refers to the ability of IgA to prevent microbes and antigens such as toxins from gaining access to the intestinal epithelium
It actives complement weakly so there is minimised inflammation
What is the function of the Poly-Ig-receptor?
It’s found at the basal surface of epithelial cells and can bind to the J-chain of IgA and a little to IgM.
It enables trans-endothelial transport of dimeric IgA and pentameric IgM which helps to enrich these antibodies into the mucus
What is gut homing of B- and T-cells?
When the cells are instructed to return to the effector sites where they were primed. It happens in all tissues
Cells can only return to specific areas because they form a lock and key mechanism between them and receptors on endothelial cells
What is the function of retinaldehyde dehydrogenase (RALDH)?
It converts vitamin A into retinoic acid
What is the function of retinoic acid?
It upregulates adhesion molecules on lymphocytes in mesenterial lymph nodes or Peyer’s patches
Where is RALDH produced?
Dendritic cells in gut-associated tissues
Where do antigen-primed B- and T-cell originate from?
From naive B- and T-cells whose recirculation pattern is restricted to the blood stream and lymph nodes
What are primed B- and T-cells?
Those that have had contact with an antigen
