Exam 3 Flashcards
What are peyer’s patches and what is their general structure?
They are domed structures which have a high number of B-cell follicles and small T-cell areas.
What are isolated lymphoid follicles
They are simular to the pyeres patches they have M-cells over the organized lymphoid tissue. mostly B-cells and develops after birth.
What is the role of the mesenteric lymph nodes?
They are where lymphocytes from the peyers patches and the ILF drain into. They act as the firewall keeping intestinal bacteria from penetrating systemically, they also play a role in immune tolerance of food.
what is BALT
bronchus associated lymphoid tissue, they are normally not found in humans unless there has been the initiation of a large inflammatory response
What are the three components of GALT
This is the gut associated lymphoid tissues. They are the cryptopatches which turn into the isolated lymphoid follicles and the Peyer’s patches.
Cryptopatches develop into immature ILF by the recruitment of B-cells. They the mature ILF are the inductive sites for mucosal B a
What are the three mucosal surface associated cells?
M-cells : antigen uptake and delivery to the lymphoid tissues like the ILF and the Peyers patches.
Paneth cells: located at the intestinal crypts in associatoin with stem cells, they secrete proteins like defensins, lysozymes and phospholipases.
Goblet cells: Secrete mucus into the intestine. They have two mechanisms. The first is a basal level of mucus secretion and the second is activates secretion
What are the two effector sites and what cell types would likely to be found here?
1) the epitherlium, here there are intra epithelial lymphocytes specifically CD8 T-cells
2) the lamina propria which have more lymphocytes as cell as innate lymphoid cells.
How do naive lymphocytes get to the PP and how do they once they see their antigen immigrate to the LP
They use L-selectin (CD62L –> MadCAM-1) to leave HEV –> PP.
Once they see their antigen, the migrate to the mesenteric lymph node, get to blood via thoracid duct, make way to the intestinal lumen and then us a4B7 to integrate passed the vili epithelium and into the LP where they are needed.
How is the change in homing of T-cells initiated
Via the production of retinoic acid by the dentritic cells leading to the expression of a4B7 this also leads to Treg cells –> IL-10
What is the role of intraepithelial lymphocytes
They are CD8+ effector cells in the epithelium and they will kill off infected cells which will be replenished via the stem cell proliferation occurring on the intestinal crypts.
What are the DC cell subsets and what do they do?
1) CD11b which makes Il-23 which promotes the development of Th17 cells which mediate an extracellular pathogen response.
2) CD103 which do two things, they induce the production of Treg cells which make IL-10 and they also make RA which induces the expression of gut homing receptors a4B7. Remember that RA also causes Treg differentiation
What are some immune sensing receptors in the mucosa? What do they do?
TLRs (low expression), RIG-1, NOD-like-receptors
They sense bacteria, intestinal injury and mediate barrier functionality.
