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18 Cards in this Set
- Front
- Back
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Define Oral Tolerance
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Ability of gut to discriminate pathogens that require protective immune response from normal bact. and dietary antigens
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Role of Peyer's Patches?
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Antigen-driven priming and maturation of native B and T Lymphocytes
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Peyer's Patches are cellular components of GALT (gut-associated lymphoid tissue). What are other immune cells of GALT?
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T and B cells
dendritic cells microfold cells Paneth cells Intraepithelial lymphocytes (IELs) |
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List the sits where B and T cells perform their effector functions in the gut
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B and T cells mature in Peyer's Patches --> Go to Mesenteric Lymph Nodes via lymphatics --> Migrate back to lamina propria of bowel.
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Where can M cells be found in the gut?
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Found in: Follicle-Associated epi of Peyer's Patches.
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Whats the major Function of M cells?
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Transport organisms and particles from gut lumen into immune cells across epi barrier and thus are important for stimulating mucosal immunity
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Where in the gut are IgA-producing B cells activated?
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Activated in Peyer's Patches
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What two cytokines drive B cell isotype switching from IgM to IgA?
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TGF-B and IL-10
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Whats the route of B cell and T cell migration following activation in the Peyer's Patch?
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Peyer's Patch --> Take residence in intestinal tract by migrating to mesenteric lymph nodes then to circulation through lymph system, then finally to lamina propria of gut.
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How is IgA transported onto mucosal surfaces?
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Dimeric IgA secreted into LP --> Binds/Forms covalent complex with Polymeric Immunoglobulin Receptor expressed on basolateral aspect of intestinal epi cell --> Complex actively transported across epi cell to apical surface
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What does Dimeric IgA form covalent complex with on epi cells?
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Polymeric Immunoglobulin Receptor
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What are the major protective functions of secretory IgA?
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Prevents luminal antigens, micro-organisms and other foreign proteins from penetrating the intestinal surface and can neutralize toxins and infectious organisms. It can also regulate composition of microbial environment of gut and limit local inflamm induced by pathogen-associated molecular patterns, such as LPS
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Whats the function of lamina propria dendritic cells?
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Breach intestinal epi to reach out into luminal environment = raises possibility that sampling of luminal antigen will occur outside Peyer's Patches
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What are the types of intestinal epi cells in humans and where are they found in intestine?
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CD8 T cells = in small intestine
TCR cells alpha-beta TCR CD4+ T cells alpha-beta TCR CD8+ T cells = predominate in small intestine double negative cells |
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Where are Paneth cells found in intestine?
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Base of Crypts of Lieberkuhn in intestinal tract
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What do Paneth cells do?
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Do innate immunity - located at base of crypts of Lienerkuhn in small intestine. Contain Anti-microbial peptides, alpha-defensins
Alpha-defensins help agains Gram -, Gram +, Viruses |
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Without Paneth cells, what infections are you more susceptible to?
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Gram -, Gram +, Viruses
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How do intestinal epi cells participate in mucosal immunity?
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Maintain homeostasis by modulating lymphocyte activation
Control local inflamm Act as Antigen-presenting cells , recognize/respond to bact./viral via expressing nucleoside-binding oligomerization domain and Toll-Like receptors Produce chemokines and Cytokines that influece T regulatory cell expression in intestine |
