Term
what is the role of adjuvent?
How does it alter antigen? |
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Definition
- enhances immunogenicity
- Alum makes the immunogen particulate and readily ingested by APC's |
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Term
| Eight attributes contribute to immunogenicty and what direction? |
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Definition
- size (larger)
- Dose (intermediate)
- Route (subcutaneous is better, intragastric is worst)
- Composition (complex)
- Form (particulate and denatured)
- Similarity to self protein (multiple differences better than only a few)
- Adjuvants (slow release, bacteria)
- interaction with host MHC (effective) |
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Term
| Why won't even animal insulin be immunogenic? |
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Definition
| too small, less than 10,000 daltons |
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Term
What antibodies are usually formed in response to T-independent antigens?
- are they mutated?
How does their affinity compare to T-dependent?
Most important type of antigen for T-independent response?
|
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Definition
- IgM
- not somatically mutated
- lower affinity
- bacterial polysaccharides |
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Term
| Biggest differences between T-independent vs T-dependent antigens: |
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Definition
T-independent:
1) no germanl center formation
2) No somatic hypermutation
3) No memory
4) No isotype switching |
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Term
What is the first extracellular step of activation of nuclear transcription facotrs that activate B cell ?
What is the first intracellular step? |
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Definition
- crosslinking of BCR by antigen
- phosphorylation of the tyrosines on ITAM's (Iga, IgBI) |
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Term
| What happens if antibodies do not neutrlaize a pathogen after binding to it? |
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Definition
| - promote destruction of the pathogen by activating other effector mechanisms such as compliment and Fc receptor-mediated killing |
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Term
What type of antibody do most Fc Recptors bind?
What is the exception to this? |
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Definition
|
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Term
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Definition
- intracellular chains of Iga and IgB that associate with antibodies (BCR's) on B cells and Fc Receptors on different types of cells.
- their phosphorylation is the beginning on transcription factor upregulation during B cell activation |
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Term
| Difference between antibody bound to antigen vs. one that is not? |
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Definition
| - antibody must be bound to antigen to have it's Fc domain interact with and crosslink Fc receptors on B cells. |
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Term
| What proteins are responsible for phosphorylation of ITAMs? |
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Definition
| -Scr protein tyrosine kinase: Fyn, Blk, Lyn |
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Term
T-dependent pathway
- how does it start? |
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Definition
- BCR interacts with antigen, which is internalized and presented by MHC II
- TCR of T-cell recognizes the peptide in the context of the MHC II and produce cytokines which activate B cell to proliferate and differentiate to plasma cell |
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Term
| B cell activation requires two signals: |
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Definition
1) interaction of BCR with antigen
2) Interaction of TCR with peptide/MHC complex and interaction between costimulatory molecules CD40 and CD40L |
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Term
What type of antigen is usually T-dependent?
What type of antigen is usually T-independent? |
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Definition
T-Independent: Carbohydrates
T-dependent: proteins |
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Term
| What cytokines are produced by T cell after interaction with B cell that causes B cell differentiation and proliferaiton? |
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Definition
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Term
| Explain B cell activation with polysaccharide? |
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Definition
- H. Influenxa polysaccharide is chemically linked to to a proetin. B cells bind the polysaccaride and present the protein to T-cells
- T cell then in turn stimulates B cell to be polysaccharide specific |
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Term
Primary vs. secondary antibody response:
What antibody is present in primary? secondary?
Which is faster?
When does affinity increase? Why?
When is titer higher?
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Definition
-Primary: IgM
-Secondary: IgG
-Primary is slower
- Affinity increases at the end of the primary response due to somatic hypermutation
- secondary response |
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Term
Which gene is rearranged in isotype switching?
When does it occur?
What is it regulated by?
What is the name of the mechanism? |
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Definition
constant part of heavy chain
occurs during T-dependent response
mediated by T cell cytokines
- somatic recombination |
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Term
| Steps in somatic recombination |
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Definition
1) DNA loops out
2) intervening DNA is excised and delated from the genomic DNA |
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Term
What enzyme is required for isotype switching?
What are the switches to? |
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Definition
AID
- from IgM to IgG, IgA, IgE |
|
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Term
| Where/what are switch sites? |
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Definition
| - upstream repeat sequences with high degree of similatarity |
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Term
| Three mechanisms by which antibodies mediate humoral immunity |
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Definition
1) Neutralization: antibody prevents bacterial adhesion
2)Opsonization: Antibody promotes phagocytosis
3) Complement: antibody activates compliment which optimizes optsonitzation |
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Term
Three things that occur in germinal centers?
Which part of germinal center do two of these occur? |
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Definition
1) somatic hypermutation
2) Class switch recombination
3) Development of memory B cell
- Dark Zone: isotype switching, and hypermutation |
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Term
How does a B cell prevent apoptosis in follicular tissue?
Wht do tehy do next? |
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Definition
- interact with antigen bound to folicular dendritic cell after hypermutaiton
- these then present antigen to T helper cells CD4.
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