Ch. 3: mucosal immunity

Question 1

most lymphocytes found and majority of IgG produced in___

Answer 1

MALT

Question 2

why are microbiota not elimnated from intestine
what receptors are expressed?
what transcriptional effect?

Answer 2

high expression of tollip
low expresion of TLR4 and TLR2
use of PPARy to block NFKB translocation to the nucleus bc block degradation if iKb which inhibits NFKB.

Question 3

what determines whether a Treg is made vs TH1 or TH2?

Answer 3

if not penetrated, dendrite gives weak stimulation and genrates regulatory T cel lresponse with IL10 and CD25.
If penetrates epithelial barrier, then full blow TH1/TH2 develop. and express IL12 or strong cytokine.

Question 4

what is the importance of paneth cells?
what is special about M cells?

Answer 4

have TLR that respond by secreting antimicrobial peptides. they are most similar to NKT cells.

m cells don’t have mucus nor microvilli and are there just to catch pathogens. BUt some pathogens also use that as aconduit. when they take up pathogens, they do so by endocytosis and phagocytosis. Or antigen is transported across.
then DC are recruited by IEC with chemokines CCL9, 20

Question 5

CCL9
CCL20

Answer 5

IEL recruit DC when M cell ingest pathogen

Question 6

where do DC present to T cells in epithelial barriers
where are there lymphoid compartments
how do you home lymphocytes to intestinal villi?
what is on the epithelial csll vs the lymphocyte?
what does the IEC produce to attract lymphocyte?

Answer 6

present to T in Peyers patches and mesenteric Lymph nodes
there are lymphoid comparments inside intestinal villi
homing: alpha4:beta7/MadCAM for LP
IEL hae alphaE:beta7/ E-cadherin

think E for epithelial

IEC produces CCL25 to attract the CCR9 T/B cells

Question 7

what are other ways to sample intestinal contents without destroying the epithelial barrier?

Answer 7

FCRN- depenent is where it is ingested and carried to DC.
apoptosis is where icell dies and pieces taken up by DC
antigen capture is where DC squeezes through

pathogens can also use these same mechanims

Question 8

how is IgA made in the gut?
what does it do
how is IgA deficiency overcome?

Answer 8

under the epithelial cell, class switch to IgA. IgA secretes dimer J-chain and it is transcytosed across the epithelium and cleaved and secreted as dimer. 
several functions:
1. neutralize pathogens
2. endosomes 

overcome IgA deficincy with IgM

Question 9

what is the function and mechanism of Intraepithelial epitheial lymphocytes (IELs)
what ligand do they all express?

Answer 9

CD8 like so
1) MHC class I presentation and then kill with fas/ perforin/ granzyme
2) Cell stress and release MIC-A,B which binds IEL NKG2D+ and also stimulate killing
all express NKG2D+ ligand

Question 10

mice given ovalbumin?

Answer 10

immunized 7 days later throughout all of body. oral tolerance give immunity.