Lecture 13: Mucosal Immunity Flashcards
True or false: 70-80% of all IgG producing cells in the body are physically located within the tissues of the mucosal immune system
TRUE
What kind of cells initiate a mucosal immune response?
inductive cells
What kind of cells enact the mucosal immune response?
effector cells
What are the 7 components of the mucosal immune system? (MALT)
1) GALT (gut)
2) BALT (bronchial)
3) NALT (nasal)
4) Genitourinary
5) Lacrimal
6) Salivary
7) Mammary
Give 2 reasons for why mucosal immunity is so important
1) pathogens enter our bodies via mucosal surfaces
2) mucosal surfaces cover a huge part of our bodies
What are the leading 2 causes of death from mucosal infections?
1) acute respiratory infections
2) diarrheal disease
What kind of cells predominate in the absence of infection?
activated/memory T cells and Tregs
What immunoglobulin dominates in mucosa?
IgA
What are the 2 distinct compartments that make up the mucosal immune system?
1) epithelium
2) lamina propria
What cell type stretches from the lamina propria to the surface of the gut (thru the epithelium) to sense bacteria?
dendritic cells
What are the 2 patterns of lymphoid cell arrangement in the gut?
1) Scattered (inductive)
2) Effector (organized like Peyer’s patch)
What kind of cells take up antigen from the gut?
M cells (microfold - the lumenal face is much different looking)
How does the M cell process antigen?
it doesn’t really, it endocytoses it then transports it across the M cell in vesicles before releasing it at the basal surface
Once pathogen has been funneled from the lumen to the lamina propria via the M cell, what happens?
DCs bind the antigen and activate T cells
Where do the T lymphocytes that encounter the DC in the lamina propria of the gut come from?
Peyer’s patch
Once activated, where do the T cells go?
leave the mucosal site and travel to the mesenteric lymph then the lymph
Expression of what on activated T cells helps them to home to the lamina propria of the gut?
a4b2 and CCR9
Where do lympocytes exit the lymph and enter circulation?
thoracic duct
What are 4 methods of antigen uptake in the mucosa?
1) M cells across the epithelium
2) Fc receptor transport
3) apoptosis dependent transfer
4) antigen capture
True or false: lymphocytes activated in mucosa can home to other mucosal sites?
True
(which is why administering antigen at one mucossal site results in specific antibody production at distant mucosal sites)
Why is there more IgA in the gut than other isoforms?
because B cells in the mucosa are selectively induced to produce dimeric IgA rather than other isotypes
What class of T cells specifically is important in MALT?
CTLs (cytotoxic T cells)
Does mucosal immunity result in systemic immunity?
YES (serum antibodies can be detected indicating that a mucosal encounter with antigen generates subsets the T and B cells that home to mucosal sites as well as spleen and regional nodes)
Does systemic immunity result in mucosal immunity?
NO, only the reverse is true
