Lee - Mucosal Immunity

Question 1

Mucus

Answer 1

• the major contributors to viscosity are mucin glycoproteins
  Mucin is permeable to macromolecules such as antimicrobial molecules and Igs so they can let them through to attack microbes. Mucin is impermeable to microbes so it keeps them out.

Question 2

Intercellular junctions

Answer 2

• the space in between cells so as not to let anything through.
  Tight junctions at the lateral skies - Claudine’s and occludins
  Adherens junctions called cadherins
  Desmosomes

Question 3

Antimicrobial peptides

Answer 3

Cathelicidins And defensins. Kill microbes either directly (defensins) or through secondary mechanisms (Cathelicidins)

Question 4

Intraepithelial lymphocytes

Answer 4

Small mononuclear lymphocytes interspersed between epithelial cells.

• express NK receptors
• express integrity so that they can bind to the E-cadherin on the epithelial cells

Question 5

N aural IELs vs inducible IELs

Answer 5

Natural is what you are born with in terms of lymphocytes. Inducible is that which you are introduced to and begin to make antibodies against them.
- you natural antibodies stay constant throughout life and the inducible numbers grow through the the years.

Question 6

What are the dominant Igs in the mucosal surfaces?

Answer 6

IgA and IgM

Question 7

Transcytosis of secretory Ig. How does the body meet mucosal antigens?

Answer 7

Basically the antibody binds to a molecule called pIgR - polymeric immunoglobulin receptors - and causes it to go up into the epithelial cell and then out the other side into the lumen. It then catches all of the necessary antigen and then comes back to the lamina propria and introduces the antigen to the APCs in order to create a memory and an immune response.

(Antigens can also be taken up by M cells. Dendritic cells can also extend their arms and try and reach into the lumen to grab the small molecules)

Question 8

M cells

Answer 8

M cells can internalize pathogens in the mucosa. It then presents them directly to the dendritic cells that are lying just under earth. The B cells and T cells are lying just underneath as well.

Question 9

Wnt and Notch pathways

Answer 9

Wnt pathway is responsible for telling the epithelial stem cells to proliferate
Notch pathway is responsible for telling the cells what they will become and where they will reside.