L11 - Mucosal immunity 1 summary

Question 1

SUMMARY PART 1

i) what type of barriers do immune defences in the gut involve?
ii) name two accumulations of lymphatic tissue in the GI tract and where they are found
iii) name two important inductive sites
iv) name two important effector sites

Answer 1

i) mechanical - spec and non spec
ii) Waldeyers ring (tonsils) and peyers patch (terminal ileum)
iii) inductive sites = peyers patch and mesenteric LNs
iv) effector sites = lamia propria and epithelium

Question 2

SUMMARY PART II

i) what is the dome of a peyers patch covered in? what type of cells are found here? what is function of these cells?
ii) which type of cells do PP give rise to? which two molecules cause the cell to produce a specific Ig?
iii) which cells do naiive B cells recognise antigen on? where are these found?
iv) which cells do T cells recognise antigen on?

Answer 2

i) dome of PP is covered in epithelia that contains M cells
- M cells deliver gut antigen to the PP

ii) PP give rise to IgA producing plasma cells
- NO and TGFb cause B cells to predominantly produce IgA

iii) naiive B cells recognise antigen on follicular dendritic cells in the follicles (not professional APCs)
iv) T cells recognise antigen on dendritic cells (profesh APCs)

Question 3

SUMMARY PART III

i) what increases chance of B and T cells meeting? (2)
ii) what really gets the immune system going?
iii) how to T and B cells leave the PP? where do they return to? how do they get there? (2) does this depend on high endothelial venules?
iv) what is the cellular recirculation pattern referred to?

Answer 3

i) proliferation and increase in number following antigen recognition
ii) B and T cell co-operation

iii) B and T cells leave the PP via afferent lymphatics
- return to the gut via thoracic duct and bloodstream
- does not depend on HEV like naiive B and T cells

iv) cellular recirculation pattern = homing