Mucosal Immunology and Food Allergy Flashcards
What is present within microvilli?
Artery, vein, and lymphatic projections.
Purpose of microvillous lymphatic projections
Important in trafficking immune cells from draining lymph node
Paneth Cells
Produce anti-microbial substances
Oral tolerance
Oral feeding of antigen to tolerize, subcutaneous injection of antigen and adjuvant leads to tolerance.
How are nature/form/dose of the antigen involved in oral tolerance induction?
Protein > Carbs > Lipids, Soluble = tolerogenic, particulate = nontolerogenic, low dose = regulatory t cells, high dose = anergy/deletion
Do neonates tolerize?
No.
How is the immune system hyporesponsive in the gut? Why?
Macrophages and DC’s have fewer TLR’s, Lymphocytes are difficult to activate and undergo apoptosis quickly. So it won’t respond to commensal bacteria.
What do T regs do in the gut to decrease lymphocyte response?
Secrete IL-10 and TGFß.
How is IgA secreted into the lumen?
Packaged and released through the IEC, binds to viruses and bacteria, prevents their adhesion to epithelium.
Three ways antigens are taken up in the gut?
Direct sampling via dendritic cells, which extend a process between IEC’s to lumen. Movement into Peyer’s Patches via M cells. Movement through/ in between IECs for contact with macrophages and T cells.
Which organisms do M cells almost exclusively transport?
Viruses
Peyer’s Patches
Have circulating T cells and large follicular zone with B cells. Generate antigen responding cells which move through mesenteric lymph nodes to circulation, then back into lamina propria.
Pathway from GALT to MALT
Gut associated lymphoid tissue to MLN, cells move through thoracic duct to heart, then back to MALT.
Th1
Induced by IL-12, produce IL-2 and IFNgamma. Cause granulomas.
Th2
Induced by IL-4, produce IL-4. Cause hypersensitivity
Th17
Induced by TGFß and IL-6, produce IL-17 and 22, which release antimicrobial substances from IEC’s.
Treg
Induced by TGFß. Cause tolerance
Crohn’s Disease Histological Hallmark
Granulomas
UC Histological Hallmark
Loss of surface cells to create pseudopolyps.
Celiac Disease
Immune response to gluten (IL-15 by IEC and IFN gamma by T cells). Villi will flatten due to crypt hyperplasia. Causes malabsorption.
Two types of allergic responses
IgE mediated (anaphylaxis, urticaria, asthma, rhinitis), Cell-mediated (gastrointestinal reactions like enterocolitis, enteropathy, celiac)
Enterocolitis symptoms and mechanism
Early onset (birth-9mo), vomiting, bloody stool, diarrhea. Caused by milk, soy, rice, oats. Caused by reduced TGF-beta receptors and increased TNF alpha expression.
Allergic Eosinophilic Esophagitis
Falls between IgE and Non-IgE mediated. Furrows in esophagus, rings, white plaques of eosinophils.
Hygiene Hypothesis
Kids aren’t getting exposed to antigens, so they develop allergies.
