Lec 33 Flashcards
What cells produce IgA?
IgA-producing palsma cells in lamina propria –> transported by secretory component produced by epithelial cells
What is action of secretory IgA?
non complement fixing = non-inflammatory
sequesters luminal mirboes and neutralizes toxins
directs bacteria to M cells
What are the 3 major paths that antigens are presented in the GI tract?
- M cells = specialized transport of antigens into cell to present to APC
- direct sampling of antigen by dendritic cell extending a process through intact epithelium into the lumen
- soluble antigen enters by transcellular [non-inflammatory] or paracellular [inflammatory] route
What is oral tolerance?
Ag specific suppression of immune response to orally administered antigens
What are the four types of T cells in the gut?
- intraepithelial lymphocytes
- lamina propria lymphocytes
- peyers patch T cells
- mesenteric lymph node T cells
What is the role of vitamin A in GI?
induces lymphocytes to start expressing certain receptors
What is role of paneth cells in gut?
produce antimicrobial peptides to protect gut stem cells
What is the role of gut bacteria in immunity?
repair epithelium, induce speicifc T cells; create competition
What does NOD2 defect cause?
defective bacterial sensing, defective defensin production
persistent intracellular bacteria
What are environmental triggers of IBD?
- antibiotics
- diet
- acute infections
- NSAIDs
- smoking
- stress
How does HIV promote liver disease?
accelerates microbial translocation from the GI tract
