16 Mucosal Immunity Flashcards
Is mucosal immunity a sterile environment?
No dirty environment. Systemic immunity is sterile
Systems of mucosal immunity?
gut, airway, urogenital tract
Where are 75% of the immune systems cells located?
mucosal immunity
do microbes outnumber host cells?
10:1 yes
T or F —activated/memory T cells predominate in the absence of infection in mucosal immunity?
True
Are immune responses down regulated in mucosal immunity?
yes—there are also inhibitory macrophages and tolerance-inducing DCs
Why is mucous secreted by gut and respiratory cells?
keep bacteria moving to prevent adherence
what are antimicrobial peptides that insert into and lyse microbial membranes?
defensins
What are alpha defensin made by?
PMN/NK
Where are alpha defensins found in?
Paneth cells of gut and female urogenital tract
What are beta-defensins expressed by? where are they located?
epithelial cells and are found in airway, gut, mammary glands, and pancreas
What do histatins do?
fight infections in the oral cavity
are cathelicidins active with gram + and - bacteria?
yes
What cells pass microbes over to APCs in the follicles?
Mcells
T or F –M cells lack glycocalyx on cell surface
true- allow them to endocytose Ag
On what surface of the intestine are M cells associated with lymphocytes?
basolateral
t or F–basolateral side of m cells are pocketed?
true—lymphocytes and DCs snuggle
What cells proliferate from M cell activation?
particularly B cells so they can exert effector functions downstream
Are overactive immune responses in the gut desirable?
No–too much Ag…it would devastate the tissue
What suppressive functions are there in the gut immune regulation?
Tregs
Cytokines IL 10
What are CD8 cytotoxic T lymphocytes interspersed between epithelial cells?
IELs composed of both CD8 alphabeta and gamma/delta. Regulatory and cytolytic functions.
What is binds to thymus leukemia antigen expressed by mucosal cells and preventing proliferation of IEL?
CD8aa homodimers
Can IEL possess FasL, perforin and cytolytic granules?
Yes–activated or memory phenotype for quick response
What acts as a sink for IL-2 and secretes suppressive cytokines like IL-10?
Tregs
Trafficking of lymphocytes that were induced in the MALT don’t use CD62L (L selection). Wht do they use?
a4B7 integrin to bind to mucosal addressin cell adhesion molecule [MadCAM-1]
Where is 90% of IgA in the body secreted?
b cells in the mucosal sites–IgA is made 2:1 over IdG in the body although IgG is more dominant in the serum
Path of Mucosal B cell response?
prime in MALT by T cells—->proliferate—->home to distal mucosa of effector sites—->receive more signals to differentiate into plasma cells—->secret IgA
What crosses epithelial barriers in dimeric fashion via pIgR?
IgA
What neutralizes and binds up bacteria and other microbes so they can’t enter the body and harm the host?
IgA
What are the properties of IgA?
inhibit bacterial adhesion
inhibits macromolecule absorption
inhibit inflammatory effect of other isotypes
neutralize virus, bacteria, toxins
what allows IgA to bind mucus keeping it in the gut?
PIgR
T or F- PigR can also bind to certain bacterial proteins such as E coli?
True
what allows for formation of IgA dimer?
J chain
Where do CD4 T cells traffic to in the gut?
mesenteric Lymph nodes
T or F–In mesenteric lymph nodes, CD4 T cells can induce class switching of B cells from IgM to IgA?
True
What provide passive immunity to neonates?
IgA
Gluten sensitivity, wheat allergy, and celiac disease is a result of what?
uncontrolled T cell activation—->inflammation and loss of villi in mucosa brought on by loss of tolerance to food antigens
Inappropriate inflammatory reactions to commensal microbials in the gut are associated with what 2 diseases?
Crohn’s and ulcerative colitis
Which cells activate the IEL cells in the gut? How do they activate(receptors)?
Intestinal cells are the activators through on classical MHC.
TCR binds to CD1D
CD8 binds to gp180
