2: Immunology - Mucosal immune system Flashcards
Which lymph nodes are found in the gut?
Peyer’s patches
Which component of Peyer’s patches have ruffled membranes?
What is their function?
M cells
Antigen sampling and absorption
By which two processes do M cells take up antigen in the Peyer’s patches?
Endocytosis
Phagocytosis
Which immune cells bind to the antigens absorbed through M cells and present them to other immune cells?
Dendritic cells
Which immune cells can project themselves across the epithelial membrane of the gut to sample antigen in the gut lumen?
Dendritic cells
Which types of T cell are found in the epithelium of the gut?
Cytotoxic T cells (CD8+)
Which types of T cell are found in the lamina propria of gut cells?
Helper T cells (CD4+)
Which cells, found in the lamina propria, are activated by dendritic cells presenting antigen?
T cells
How do T cells reach the basolateral membrane of gut cells?
Bloodstream
Through which lymphatic vessel do activated T cells have to drain to reach the bloodstream?
Thoracic duct
What is an MA?
Molecular address signal - binds to effector T cells which need to return to that area in the gut
Which signals direct migration of T cells through the gut epithelium?
Chemokines
Adhesion molecules ___ T cells to the gut epithelium.
T cells then migrate through the epithelium by following a ___ gradient.
anchor
chemokine
Which disease causes individuals to initially lose up to 70% of memory T cells in their gut?
HIV
How are memory cells transferred from mother to child?
Which type of immunity is this?
Breasfeeding
Passive immunity
Which antibody is most common in the intestinal mucosa?
IgA
Which antibody is most common in the systemic immune response?
IgG
Which antibody is the first to appear, but not the most abundant, in the intestinal and systemic immune responses?
IgM
Which type of antibody is most abundant in breast milk?
IgA
IgA is a (monomer / dimer).
dimer
Some immune cells in the gut serve only to produce (IgA / IgM), all the time.
IgA
Where are IgA-secreting cells found?
Lamina propria
i.e not the epithelium
How does IgA enter epithelial cells from the lamina propria?
Endocytosis
After passing from the lamina propria to the epithelium, where is IgA secreted?
By which process?
Gut lumen
Exocytosis
What does secretory component do for IgA?
Allows it to persist in the gut lumen for a while without being digested by proteolytic enzymes
IgA stops ___ and ___ from binding to the gut epithelium.
toxins
pathogens
Apart from preventing pathogen/toxin binding, IgA can ___ antigens by internalising them in a vesicle.
neutralise
While being excreted from the gut by exocytosis, IgA can ___ pathogens back to the gut lumen.
export
Which immunoglobulin is very important in protecting the gut epithelium?
IgA
What are intraepithelial lymphocytes?
Mainly cytotoxic T cells (CD8+)
What do intraepithelial lymphocytes do?
Kill infected (virally or otherwise) epithelial cells from the basolateral side
What protein displays self antigen on the surface of all body cells so that they aren’t killed off by immune cells?
MHC Class I
The immune response to protein is (stimulated / inhibited) when that protein is administered orally.
inhibited
The immune system is hyporesponsive to antigens which are ingested with ___.
food
When exposed to commensal bacteria, dendritic cell maturation is (inhibited / stimulated).
inhibited
hyporesponsiveness of immune system in response to food
When exposed to invasive microorganisms, dendritic cells are (inhibited / activated).
activated
What four diseases can occur when the mucosal immune system is dysregulated?
Primary immunodeficiency
Allergy
Coeliac disease
IBD
