Chapter 10 Flashcards
What is the systemic immune system?
Body’s response towards pathogen penetration of the skin
What is the Mucosal Immune system?
Body’s response towards pathogen penetration of the mucosal surfaces
Differences between the systemic and mucosal immune systems?
System works on clearing the infection whereas mucosal works on prevention. Location and inducible responses differ as well. Mucosal also restricts growth and location of commensal microorganisms
What are “commensal” organisms?
organism that uses resources such as food from a host without harming the host such as a parasite
MALT?
Mucosal Associated Lymphoid Tissue
-Epithelial cells coated with Mucus containing protein and enzymes that protect cells
GALT?
Gut associated lymph tissue, part of MALT
Defensins? their processes and production?
antimicrobial peptides that kill pathogens
-Amphipathic molecule that enters pathogen’s cell for lysis
-Also neutralize + unfold microbial toxins to be susceptible for proteolytic denaturation
-Created by Paneth cells + epithelial cells in skin and lungs
Subsets of Gut Epithelia Cells?
Enterocytes
M-Cells
Goblet Cells
Paneth Cells
Intestinal Stem Cells
Enterocytes?
Intestinal cells within the villi of epithelium that absorb nutrients
M-Cells?
Transport microbes and antigens into the intestine
Goblet Cells?
Produce and secrete Mucous
Paneth Cells
Secrete AMPS (Anti-microbial peptides)
Mucins?
glycoproteins produced by mucosal epithelium, protecting the mucosal epithelium
-Trap microorganisms before their interaction w/other cells
-Large molecule that O-linked glycoslyated with (-) charges
Ways Commensal microorganisms can assist the gut in digesting food and maintaining health?
- Synthesize metabolites that are not made by humans
- Increase digestive
efficiency by breaking down plant fibres that humans do not have the enzymes for - Inactivates toxic substances
- Outcompete pathogens
What does Gnotobiotic mean?
An individual with no microbiome, being germ free
Why can Commensal Organisms become pathogenic?
If commensals breach the gut epithelium, they can become pathogenic. Hence why specific IgA is made against commensals and continuously secreted into gut lumen to control population size.
IgM class switch to IgA
What is the lamina propria?
connective tissue under the epithelium which houses mature B cells for prevention of disease within the Gut lumen (Effector Cells)
What are villli?
Large surface for absorption
What are peyer’s patches?
secondary lymph organ on the wall of small intestine that houses naive B + T cells
Immunosuppressiveness performed by?
Dendritic cells secreting IL-10 after binding to antigen in the peyer’s patch to prevent activation of T cells to make inflammatory cytokines
Differences between the subclasses of IgA?
IgA1 - longer, flexible making it more susceptible to proteolytic attack
IgA2 - carbohydrate protection
What are intestinal macrophages? and how are they NOT APC?
Eliminate pathogens without the state of inflammation
-shorter life span
-Express MHC 2 without B7 protein, making it not a antigen presenting cell, as they’re not able to induce an adaptive immune response by activating T cells
What are Intraepithelial lymphocytes?
CD8 T-cells that contain toxic granules
How is oral tolerance gained?
From food products, dendritic cells containing CD103 take up the food at the peyer’s patch, further being sent to the mesenteric lymph node to present to Treg cells (express FoxP3 TF)
-These Trees suppress immune response of the food antigens, while higher concentration of antigen induces anergy of those Tregs
B cell activation in the MALT explained?
Once presented via MHC by dendritic cells…
-B cells differentiate into plasma cells that secrete IgM or Memory cells that secrete IgA
-These neutralize pathogens and export pathogen from lamina propria
