Specialized Immunity at the G.I. Epithelial Barriers Flashcards
Name the specialized cells of the gut an epithelial tissue that are responsible for Ag sampling.
Gut- M cells.
Epithelia- delta/gamma T cells.
At sites of organized mucosal lymphoid tissue, what specialized cell delivers Ags across epithelial barrier?
Microfold (M) cells.
Epithelial cells produce anti-microbial peptides called and what cells produce them?
Defensins. Produced by paneth and epithelial cells.
The physical/ chemical barrier is formed by several viscous proteins called?
Mucins, which include secreted and cell surface glycoproteins.
The apical surface of GI epithelial cells is coated with a membrane-bound mucin called?
Glycocalyx
Where are alpha and beta defensins found?
Alpha- small bowel produced by paneth cells.
Beta- colon produced by epithelial cells.
What receptor recognizes bacterial flagellins and where is it expressed?
TLR5, expressed exclusively on the basolateral surface.
B cell class switching to IgA (T dependent) is stimulated through the action of what two molecules?
CD40L binding to CD40 together with the action of TGF-beta.
What ligands activate T-independent IgA class switching?
BAFF, APRIL, TGF-beta.
What is the main difference is T dependent vs T independent IgA class switching?
T dependent will yield high affinity IgA Abs and T independent will yield low affinity IgA Abs towards intestinal bacteria.
Th17 cells are found where in the G.I. tract?
Small bowel
What two cytokines do Th17 cells secrete and what are their functions?
IL-17, IL-22: Induce the expression of mucins and beta defensins.
Name 3 cytokines that are involved in maintaining homeostasis in the gut.
IL-2, IL-10, TGF-beta.
Commensal microflora controls inflammation via inhibition of what?
NF-kB
NLR family receptors for flagellins are expressed where in the intestinal epithelial cells?
Cytosol.
