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24 Cards in this Set

  • Front
  • Back
What is MALT?
mucosa assosiated lymphoid tissue, a highly specialized immune system that protects the mucosal surfaces. Largest mammalian lymphoid organ system.
Why does knowing which compartment an immune response begins important?
Where the initial immune response starts is where the effector cells will come back to.
What makes the job of the MALT difficult?
It needs to distinguish not only between self and non-self, but harmulf non-self and nonharmful non-self.
What cells are the central component of an effective mucosal immune response?
B-cells. The main mediator is secretory IgA and to a lesser extent secretory IgM.
Why is IgA so important to the mucosal immune response?
It is resistant against common intestinal proteases and it does not interact with complement. It inhibits adherence, neutralizes viruses, and neutralizes enyzmes and toxins
What is the critical class swith factor that will cause the B-cell to secrete IgA?
TGF-Beta. However it also needs Th2 cytokines like IL-4, IL-5, IL-6, and IL-10. Once this occurs you are a fully competent IgA producing B-cell
What is the J-chain
Binds to the tail pieces of IgM and IgA. It stabilizes polymers of IgA amd IgM allowing it to bind the Ig receptor or secretory complement.
How do you get the IgA into the lumen?
J-chain binds receptor on the basal surface of epithelium, transcytosis to lumen, receptor is cleaved with polymeric IgA and J chain.
What are the two sites of the mucosal response?
inductive sites (peyer's patches) with lots of alpha-beta T-cells with a lot of CD4 Th1 and Th2 cells. The effector site with lamina propria lymphocytes mostly CD4 Th2 and intra epithelial lymphocytes CD8+
How are IEL localized to the intra columnar villi spaces?
They express specific integrin that localize them to the inter epitheim of the mucosal immune system
What kind of cytokine profile is released from IELs?
IFN-gamma and TNF-alpha.
What is the role of the IELs?
possibly destroy epithelial cells that have underone transformation, regulatory role in oral tolerance
What do M-cells do?
Sample the environment of the lumen. Have receptors for secretory IgA. Binds IgA in the lumen and sample the environment. M-cells are in close apposition to other immune cells. This can be a good entry point for pathogens.
How do DCs play a role in the mucosal immune system?
In lamina propria have dendrites that go between cells to lumen and capture pathogens.
What receptor is important for the formation of functional dendrites
Describe the path from pathogen recognition in MALT to the activation of T-cells that enter the blood.
at the inductive lymphoepithelium pathogens are sampled and brought in via DCs or Mcells. They are directly provided to APCs, B-cells or DCs. T-cell APC interaction activates T-cell. Activated T-cells interact with B-cells. B-cell switch to IgA. activated T-cells leave and enter the circulatory system.
What happens to the T-cells that enter the blood stream?
They may undergo additional differentiation, but they ultimately return to the site of initial immune response.
IgA deficiency
most common primary immunodeficiency, less than 50ug/ml. Important for receiving blood products containing IgA b/c you can get IgE response against IgA. Higer incidence of infections of URT/LRT and GI. increased autoimmunity
chronic relapsing and remitting inflammation condition. Crohn's and Ulcerative colitis. Patients have increased numbers of activated mucosal T-cells secreting INF-gamma. IL12, IL-18, and produced drive toward Th1-TNF-alpha and IL-1. Increased IgG and complement fixing.
Crohn's disease
affects the small intestine and the colon. Thought to be associated with NOD2 (like TLR receptor) defects causing an increase in T-cell recruitment and increased inflammatory response.
Ulcerative Colitis
which predominately affects the colon in a superficial manner.
Celiac Disease
T cell mediated immune disease of the small intestine triggered b gluten. major feature include villous atrophy with a lymphocytic infiltrate, increased epithelial proliferation with crypt hyperplasia and malabsorption. CD4 mediated disease associated with HLA DQ2 and DQ8. Intraepithelial CD8 cells make it different that IBD
Oral Tolerance
give an antigen orally and come back systemically the immune system will ignore it.
The goal of oral vaccines
elicit a long lasting mucosal antibody response to an antigen, the problem is that the mucosal immune system is good at down regulating immune responses (possible use in autoimmune disease)