23- Mucosa Immunity/ GALT

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Created by
Ashley

Cards (15)

  • GALT
    Gut associated Lymphoid Tissue
  • GALT
    • Lines gut in almost all organisms
    • Important to have immune tissue here as it is a major entry point for potential pathogens
    • Lots of other ALTS as well around body (lungs, skin, cervix, etc.)
  • Epithelium

    Single layer (easy entry point)
  • Lamina propria

    Loose connective tissue, where cells are contained (Band 1)
  • Villi
    Increase surface area
  • Diffuse

    Loose cells
  • Intraepithelial lymphocyte

    Protection because of easy entry point
  • Peyer's Patch

    • Key location to coordinate immune responses and promote tolerance to healthy microbes and food
    • Organized: has specific structures, epithelial layer, separate B and T cell areas
  • Antigen Sampling
    1. Dendritic cells send cell processes between the epithelial cells into the gut lumen (occurs in the Peyer's Patch)
    2. M Cells sample material from gut lumen (occurs in Peyer's Patch)
    3. M Cells take up AG by endocytosis or phagocytosis on luminal side and determine if self or foreign
    4. Antigen is transported across M cells and released at the basal surface
    5. Antigen is then bound by dendritic cells which will go activate T cells in the Peyer's patch
    6. Helper T cells activate B cells; get IgA expression
    7. T cells have to recirculate through mesenteric lymph nodes and then return to gut with help of addressins
  • Effector Functions
    • T cells (TH17, TH1, TH2, Treg)
    • Neutrophils (Netosis: blows up and lets out all granule stuff)
    • Plasma B cells (IgA production)
    • Memory cells
  • Intraepithelial Lymphocytes in Villi (IELS)
    • CD8 cells
    • Type 1: conventional CD8 a/B T cells
    • Type 2: y/ST cc;;S
    • No positive/negative selection because don't bind MHC
    • Recognize conserved antigens (like innate immune system)
  • Mucosa Encounter
    • Harmless: microbiota, food, pollen
    • Harmful: Bacteria, viruses, parasites
  • Commensal bacteria get through the gut lining and trigger an immune response because it is foreign to this location
  • Oral Tolerance

    Causes enterocytes lining the gut to release inflammatory cytokines
  • Food antigens are presented to T cells by APC but don't elicit inflammation because there is not second signal