Mucosal Immunology Flashcards
B Cells are initially expressed where?
Follicular Zone
T Cells are initially expressed where?
Parafollicular zone
B cell class switch requires activation from which type of cell?
Helper T-Cells
T cell activation requires activation from which type of cells?
Antigen Presenting Cells
Antigen presenting cells in the gut mucosa are?
Dome Cells
Transport of antigen into the epithelium is facilitated by which type of cell?
M-cells
Does not have thick overlying mucous, with no cilia
M-cells are not phagocytic
Once stimulated by antigen, T and B cells migrate into what structure?
Lamina Propria
Properties of intraepithelial lymphocytes
Express CD8 in with an alpha/alpha homodimer
Show some cytotoxic ability
Sense damage to epithelium for replacement
70-90% of the B cells in the lamina propria secrete which type of antibody? What are the characteristics of this type of antibody?
IgA
does not produce inflammatory response
does not activate complement
opsonization occurs but with less inflamation
What is oral tolerance?
A local antibody reponse to a specific antigen can be mounted at mucosal sites in the absence of a response throughout the body.
nb: damage to intra-epithelial lymphocytes = damage to oral tolerance
What promotes trafficking of lymphocytes?
Lymphocytes express alpha4 beta7 which binds to MadCam-1 on mucosal vascular endothelium
How do the antibodies in the gut lumen inhibit bacterial propogation?
IgA(2) binds to the bacterial toxins and bacteria and inactivates them. This allows for clearance of these materials simply by having a bowel movement.
How does IgA get from the lamina propria to the lumen?
polymeric Ig Receptor (PIg-R) binds to IgA homodimer
In the lumen, what is the structure of the secreted antibody?
IgA
Two identical heavy chains with two identical light chains
bound together via J-chain
with remenant secretory piece from PIg-R
What is the receptor for IgA and what does it bind to?
IgA receptor is PIg-R which binds to J chain
