Mucosal Immunity

Question 1

What does the mucosal immune system provide?

Answer 1

The mucosal immune system provides three main functions: serving as the body’s first line defense from antigens and infection, preventing systemic immune responses to commensal bacteria and food antigens (primarily food proteins in the Gut-associated lymphoid tissue, so-called oral tolerance), and regulating appropriate immune responses to pathogens encountered on a daily basis

Question 2

Identify the different components of the mucosal immune system

Answer 2

Mucosa- layers of epithelial cells that line body passages such as gut, resp tract, & oral cavity
- Type 1 (single layer located in the gut/lungs; main Ab is SIgA)
- Type 2 (multilayered with squamous epithelium located in the mouth/nose; main Ab is IgG)
Mucous- provides a physical barrier and a matrix against microbial bacteria; contains antimicrobial peptides, antibodies, etc. (*Note mucus and mucosa are different)
Lamina Propria
Mucosa-associated lymphoid tissue includes GALT, BALT, NALT; skin = SALT

Question 3

Understand the main differences between systemic and mucosal immune responses.

Answer 3

One of the main differences is that the mucosal immunity deals more with local responses and not systemic responses. Additionally, the mucosal immune system participates in antigen sampling.

Question 4

Know the importance of commensal organisms.

Answer 4

I feel like this kind of has been answered 3 times already but…. The commensal organisms of the body provide an “Exclusionary Effect” which makes it harder for more pathogenic species to get at you.

Question 5

Some other random info

Answer 5

In GALT: epithelial layer are first contact w/ pathogen and has panteth cells (produce antimicrobial peptides), M cells (antigen sampling), goblet cells (secrete mucus); all of the immune cells are in the lamina propria (macrophages, neutrophils, mast cells, etc)
Note: dendritic cells can also do Ag sampling especially in the NALT
NALT and BALT: use nose hairs (NALT only), mucus, cilia, coughing, tonsils; Ag sampling easier here
We don’t want unnecessary inflammation because it will interrupt the tight junctions and allow bacteria to move through
SALT has little to no B cells