Mucosal Immunity Flashcards
Why is the mucosa vulnerable?
Fragility and permebaility
Physiological functions of mucosal tissue?
Gas exchange
Food absorption
Sensory activities
Reproduction
Examples of mucosal tissues?
Mammary gland Salivary gland Kidnye Uterus/bladder/vagina Conjunctiva Trachea Lungs Intestine
Anatomical features of gut mucosal system?
Organised lymphoid structures unique to mucosal sites
Effector mechanisms of gut lymphocytes?
Activated/Memory T cells predominate
Natural effector/regulatory T cells- in organised tissues
Where is the Peyer’s patch?
Only in small intestine
What are Peyer’s atches covered in?
- Covered by an epithelial layer containing M cells which have membrane ruffles
- Takes up antigens by endocytosis/phagocytosis and transported across M cells in vesicles
- To dendritic cells which activate T cells
Special skill of dendritic cells?
Can reach through epithelial layer to capture antigen from lumen of gut
How many compartments is mucosal immune system?
2
Epithelium
Lamina propria
Immune cells of lamina propria?
- CCR9
- Plasma cell
- Dendritic cells
- Mat cells
- Macrophages
- C4 T cell
Immune cells of epithelial layer?
- CD8 T cell expressing alpha E:B7 integrin and CCR9
- Dendritic cells
What happens to T cells when they are activated by dendritic cells after they’ve encountered antigens?
Enter Peyer’s patch from blood vessels
Drain through lymph nodes to thoracic duct ad return to gut via bloodstream
Most common Ig in GI tract?
IgA (80%) the IgM the IgG
Dimeric
What can IgA do?
Neutralize pathogens and toxins also while internalized in endosomes
-Can also export toxins and pathogens from lamina propria while being secreted
Special T cells in Gut?
Intra-epithelial lymphocytes (IELs) 90% are T cells