Immunological disorders of the gut Flashcards
Describe lymphocyte circulation from peyer’s patches.
Activated lymphocytes travel to mesenteric lymph nodes to proliferate, then travel in lymphatic system and from there enter blood. In high endothelial venules, L-selectin (expressed on lymphocytes) binds to mucosal addressin cell adhesion molecule which mediates rolling of lymphocyte and transmigration.
What is irritable bowel syndrome?
Results in abdominal pain/diarrhoea and constipation. Due to visceral hypersensitivity and abnormal bowel movement. Triggers: short-chain carbs and stress. Exclusion diet.
What is Coeliac disease?
Gliadin (found in gluten) hypersensitivity. Mainly in duodenum. Gliadin binds to SIgA, then binds to transferrin receptor, transcytosed to lamina propria. Tissue transglutaminase removes amide. Phagocytosed by macrophages and presented on MHC II. T helper cells secrete inflammatory cytokines - TNF and IF-gamma. B cells produce antibodies. Killer T cells. Cause flattened villi and deep crypts. Gluten-free diet.
What is Crohn’s disease?
IBD. Any part of GI affected. Triggered by pathogen - uncontrollable and inflammatory immune response. Granuloma and deep ulcers (all the way to serosa). RLQ pain. Diarrhoea, blood in stool. Liquid diet, low fibre. Surgical removal does not cure it as it can affect any part of GI.
What is ulcerative colitis?
Only affects colon. Ulcers in mucosa and submucosa ONLY, continuous and all around. T cells destroy cells - unclear why. Diarrhoea with blood. Removing colon can cure it.
