25- Mucosal Immunity

Question 1

What are the basic physical barriers in the mucosal protective mechanisms?

Answer 1

Genitourinary
- mucus: physochemical barrier
- lactic acid
- urine

GI: Peristalsis

Normal epithelium

Flora

Keratin plug (mammary gland)

Respiratory tract: turbinates, mucociliary apparatus, alveolar macrophages

Question 2

What are the basic adaptive response in the mucosal protective mechanisms?

Answer 2

• intestinal mucosal adaptive response pathway
• mucosal adaptive response (GALT, NALT, MALT)
• M cells are responsible for transcytosis of antigens across gut epithelium and release to APCs at basal surface
• lymphocyte relocation

Question 3

What is the basic form of secretory IgA?

Answer 3

• dimeric product
• majority is produced at the epithelial surface

Question 4

What is the basic function of secretory IgA?

Answer 4

IgA excludes pathogens by 3 distinct mechanisms at mucosal surfaces
- in lamina propria can bind pathogens
- within epithelial cells can bind viruses
- within the lumen can bind pathogens

Question 5

Recognize the Fc receptor transport via poly Ig

Answer 5

• FcRn transport of IgA is opposite that of the FcRn IgG transport in fetuses
• For IgA the poly Ig assists from the baso-lateral membrane through to the apical surface into the lumen

Question 6

What is the difference between immune exclusion and elimination?

Answer 6

Exclusion: entraps the pathogens in mucus, keeping the host from contracting the pathogen in the first place

Elimination: killing the pathogen if it makes it into the host immune system