Mucosal Immunology Flashcards
Inhibiting Fc receptor
FcyRIIB1
These type of B cells preferentially respond when host has previously encountered antigen
Memory B cells
How are memory B cells preferentially utilized with a previously encountered antigen?
Naive B cells are cross-linked (with IgG) via the FcyRIIB receptor, which sends a negative signal through ITIM
Why does the original antigenic sin occur?
Because memory B cells preferentially respond over naive lymphocytes
Term for the body’s first encounter with a virus, which can forever “bias” the immune response to produce antibodies tailored to the initial strain in an exposure, regardless of subsequent infections with other strains or vaccine boosters
original antigenic sin
Type of tissues that include thin epithelial layers that are exposed to the external environment
Mucosal tissues
Epithelial layers are protected by this, which contains glycoproteins, proteoglycans, peptides, and enzymes that act as barriers to infection
Mucus
Secondary lymphoid organs of the small intestine
These form small dome-like structures that contain B cell follicles and are similar to the germinal centers in lymph nodes
Peyer’s patches
Where are Peyer’s patches found?
Small intestine
Type of cell that transports antigens across the tightly-packed eptihelial layer to gut-associated lymphoid tissue
Capture bacteria from the gut lumen and deliver them and their antigens to dendritic cells and lymphocytes in the Peyer’s patch
Microfold (M) cells
Microfold (M) cells transport antigen from here and deliver them to this
Transport antigen from gut lumen and deliver them to Peyer’s patches
Highly specialized secretory epithelial cells located in the small intestinal crypts
Produce inactive precursors of alpha and beta defensins (cationic peptides that damage negatively-charged membranes)
Paneth cells
Paneth cells produce these
Inactive precursors of alpha and beta defensins
Paneth cells are found here
Small intestinal crypts
Type of cells that can extend processes across the epithelial layer to capture antigen from the lumen of the gut
Can reach between two epithelial cells to capture antigen independent of M cells
Dendritic cells
Sites for localized production of dimeric IgA and transport of these antibodies across mucosal surfaces (pIgR)
Mucosal surfaces
Are neutrophils commonly found at mucosal sites?
No; don’t want inflammation
Macrophages and DCs at mucosal sites do not express these
Also don’t produce inflammatory cytokines and/or establish strong Th1 type immunity
Do not express TLRs
This helps to limit the spread of a pathogen while also limiting inflammation at these sites
Attraction of naive B and T cells to Peyer’s patches involves these 2 chemokines
CCL21 and CCL19
Receptor on naive lymphocytes for chemokines CCL21 and CCL19
CCR7
Naive lymphocytes enter Peyer’s patches via this
High endothelial venule (HEV)
Naive lymphocytes that do not interact with their specific Ag leave the Peyer’s patches and enter this
Mesenteric lymph node
If naive lymphocytes fail to recognize their specific Ag in either Peyer’s patches or Mesenteric lymph node, they return to circulation via this
Efferent lymph
CCL21 and CCL19 are involved in this
Attraction of naive B and T cells to Peyer’s patches
Activated lymphocytes leave the Peyer’s patches and travel back to the bloodstream, and they express this chemokine receptor which homes them to distant mucosa sites
CCR9 chemokine receptor
CCR9 is a chemokine receptor on activated lymphocytes that binds this
CCL25
2 interactions involved in the recruitment of activated lymphocytes to distance sites (common mucosal system)
CCR9:CCL25
a4:B7:MAdCAM-1
Interaction that allows gut-homing effector T cells to bind to intestinal vascular endothelium and enter the lamina propria
a4:B7:MAdCAM-1
Interaction in the lamina propria where gut-homing T cells bind to chemokines expressed by the intestinal epithelium
CCL25:CCR9
What is the function of the a4:B7:MAdCAM-1 interaction?
Chemotaxis that homes activated lymphocytes to distant mucosal sites (common mucosal system)
What is the function of the CCL25:CCR9 interaction?
Homing of activated lymphocytes to distant sites (common mucosal system)
CD8+ cytotoxic T cells that intercalate into the epithelial layer in a ratio of 1 per 7-10 epithelial cells
Are antigen specific, and they use chemokine receptors and adhesion molecules to position themselves between epithelial cells
Contain intracellular granules, and can express either a:B or y:S T cell receptors along with their CD8 co-receptor
Gamma delta (y:S) T cells are usually associated with mucosal surfaces
Intraepithelial lymphocytes (IEL)
What are Intraepithelial lymphocytes (IEL)?
CD8+ cytotoxic T cells that intercalate into the epithelial layer
Class of Ig that has multiple sites for pathogen interaction across epithelial cells
(from the lamina propria, endosomes, gut surface, M cell surface; apical surface, basolateral surface, and intracellularly)
IgA
Process where IgA molecules are transported from the basolateral surface of mucosal epithelium to the apical surface
Transcytosis
IgA can deliver Ag from the apical surface to the basolateral surface via these
M cells
Why are individuals with selective IgA deficiency relatively healthy?
Other isotypes (including IgM) compensate at mucosal sites
The most common primary immunodeficiency
Selective IgA deficiency
These cells predominate in the mucosal immune system even in the absence of infection
Activated effector T cells
Bacteria gain access to lamina propria by this
endocytosis
Do bacteria activate macrophages in mucosal tissues?
yes, but do not cause inflammation
In mucosal tissues, dendritic cells travel here to activate adaptive immunity
Mesenteric lymph node
