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32 Cards in this Set

  • Front
  • Back
What are the components of the mucosal immune system?
Gut-ALT, Bronchial-ALT, Nasal-ALT, Genitourinary tract, Lacrimal glands, Salivary glands, Mammary glands.
What is the induction step of mucosal immunity?
Initiation of an immune response.
How is the sequence of the induction step initiated(use GALT as a prototype)?
Antigens enter the digestive tract and are taken up by M-cells.
What do M-cells do?
Internalize the antigen from the mucosal layer and transport it across the epithelium.
How are M-cells formed in mucosal epithelium?
The presence of lymphocytes signals their formation in the epithelium.
Where is antigen taken up by APC's, like dendritic cells?
After crossing the epithelium and entering the lamina propria.
Where is antigen presented to B and T lymphocytes in the mucous?
In the lamina propria (Peyer's patches in the GALT system).
Where do these activated lymphocytes go now?
Leave the mucosal site and travel to the nearest regional lymph node, and then to the lymph.
Where do these activated lymphocytes enter the circulation?
Via the thoracic duct.
Explain the idea behind "homing" in circulating lymphocytes.
Activated lymphocytes will travel en route to various mucosal regions in the body, whether they be near or far from the site of antigenic challenge.
What specific interactions are required for "homing" to occur?
Gut "homing" effector T-cells bind to MAdCAM-1 on blood vessel epithelium.
Target epithelial cells also express chemokines that help to recruit "homing" T-cells.
What type of Ab's do B-lymphocytes produce in the effector sites?
IgA (dimeric).
What is regional preference, in reference to mucosal immunity?
Antigenic challenge in one mucosal region will result in specific Ab production in another mucosal region, which is preferentially selected (i.e. NALT antigen will cause Ab release in the respiratory system.)
In general, how will an antigenic response in one mucosal site elicit systemic responses to another?
The first mucosal encounter to Ag generates a subset of B and T cells that "home" to other mucosal sites (by previously stated mechanisms) and to the spleen and regional lymph nodes.
What are "unconventional" T-cells?
T-cells with unusual surface receptors (which appear to develop outside the thymus) whose main function is the recognition and removal of damaged epithelial cells.
Mucosal Ab is predominantly found in what type and form?
IgA, dimeric.
Where are dimeric IgA's produced?
In the mucosal lamina propria from a secreting plasma-cell.
How does IgA transcytose over to the lumen of the mucosal surface?
Dimeric IgA binds to the pIGR, and that complex is endocytosed to the lumen for release.
What binds each side of the dimeric IgA to each other?
What molecule is cleaved and what is the fate of its cleaved particles?
pIGR is cleaved, a small fragment of it being lost and the remainder component is covalently bound dimeric IgA.
What does pIGR stand for?
Polymeric ImmunoGlobulin Receptor.
What are the 2 forms of polymeric Ab?
IgA and IgM.
What are the 4 functions of IgA at mucosal surfaces?
1) Barrier function
2) Intraepithelial viral neutralization
3) Excretory immunity
4) Passive immunity
What is the barrier function of IgA at the mucosal surface?
sIgA bind to pathogens, preventing their adherence and invasion into the mucosal tissue, neutralizing viruses and bacterial toxins.
What is intraepithelial viral neutralization?
IgA that is within the epithelial mucosa attached to pIGR, can bind to viruses in the epithelium to inactivate and excrete them.
What is excretory immunity?
Viral particles that have reached the lamina propria will bind to dimeric IgA to be endocytosed and transported back out via the pIGR pathway toward the lumen.
What is passive immunity?
sIgA in breast milk provides passive immunity through the placenta.
What are the 2 advantages of oral immunization?
1) Ease of administration (no shots)
2) Generates both mucosal and systemic immunity
What are the 2 disadvantages of oral immunization?
1) Difficulty in eliciting a robust response
2) Response may not be long-lasting.
What is the significance of commensal bacteria (i.e. intestinal bacteria) in relation to immune system development?
Colonization of commensal bacteria in the gut is required for host immune development, and a robust diversity of surface receptors.
What is one problem of mucosal immunity?
May result in tolerance to the pathogen (food particles). However, this may lead to benefits in dealing with autoimmune disease.
What are the 3 reasons to suspect IgA deficiency?
1) family history
2) high incidence of oral and respiratory infections
3) chronic diarrhea