Mucosal Immunity Flashcards

1
Q

What is the function of the mucosal system?

A

Distinguish between foreign antigens such as food and commensal bacteria (no response), and pathogenic organisms (respond)

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2
Q

What is the function of microfold (M) cells?

A

They take up antigen on the lumen surface and M cells transport them across the cell and release them at the basal surface where Ag is bound by DCs which activate T cells.

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3
Q

How is mucosal immunity activated?

A
  • Ag enters the MALT an is taken and transported across by M cells
  • DCs take them up and present them to T cells and they migrate to the mesenteric lymph nodes then enter the lymph then thoracic duct and finally circulation
  • Circulating lymphocytes will home and B cells in peripheral tissues become IgA plasma cells at effector sites
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4
Q

Will mucosal immunity generate systemic immunity?

A

Yes, it will generate both types.

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5
Q

What is the structure of secretory IgA?

A

Dimeric

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6
Q

Will systemic immunity generate mucosal immunity?

A

No

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7
Q

What is the function of Intraepithelial Lymphocytes (IEL)?

A

Kill infected epithelial cells by perforin/granzyme and Fas dependent pathways

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8
Q

How does salmonella penetrate the epithelium?

A

Enter and kill the M cells and then infect macrophages and epithelial cells and can also enter via the dendrites of DCs.

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9
Q

How is IgA transported across the epithelium?

A

IgA will bing pIGR on the basal surface of epithelial cells and the complex will be transported to the lumen for release.

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10
Q

What are the advantages of mucosal immunization?

A

Oral Administration

Generates mucosal and systemic immunity

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11
Q

What are the disadvantages of mucosal immunization?

A

Response may be short lived

Difficult to avoid the tolerance barrier

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12
Q

How to induce mucosal immunity in the tolerogenic environment?

A

Inflammation is often required.

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13
Q

How do commensals protect against pathogens?

A

Their colonization prevents pathogenic bacteria from getting a foothold in the gut

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14
Q

What is the tolerogenic response?

A

Response occurs with oral intake of food and commensal bacteria with local IgA and low serum Ab as well as no T cell response or response on re-exposure to Ag.

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15
Q

What is the immunogenic response?

A

IgA is present with local and systemic T cells and on re-exposure there is a memory response

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