Term
| Most immunogenic antigens are ______ in size |
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Definition
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|
Term
| Immunogenicity (increases/decreases) with size |
|
Definition
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|
Term
| What is MHC-restricted antigen presentation? |
|
Definition
| APCs process proteins, present their antigens to T-cells via MHC molecules |
|
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Term
True or False
Lipids & polysaccharides are highly immunogenic |
|
Definition
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Term
| How are lipid-linked antigens (glycolipids, lipopeptides) processed? |
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Definition
| CD1 molecules process them and present to antigen-specific T cells |
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Term
| What factors affect antigen immunogenicity? (7) |
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Definition
-size
-genetics
-exposure route
-chemical stability
-foreignness
-antigen dose
-complexity |
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Term
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Definition
| the antigenic determinants of a protein |
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Term
| What is an immunodominant epitope? |
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Definition
| the epitope on an antigen that elicits the most favourable host response |
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Term
| What is a cross-reactive T cell or antibody? |
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Definition
| One which is involved in recognizing similar antigens found on two different types of pathogens |
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Term
| What might cause an individual to develop an auto-immune disorder? |
|
Definition
-failure in the negative T cell selection process
-release of immunologically protected self-antigens during injury
-loss of tolerance to self-antigens
-exposure to microbial antigens which share epitopes with self-antigens |
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Term
| What might cause a hapten to become immunogenic? |
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Definition
| -covalently binding to self or non-self proteins |
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Term
|
Definition
| small molecular weight chemicals which can become activated to haptens by UV, hydroxylation, oxidation etc |
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Term
| Why do APC typically migrate to secondary lymphoid tissue after processing an antigen? |
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Definition
| Because they need to present the antigen to antigen-specific T cells, which are hard to find but found in greater concentrations in the secondary lymphoid tissue |
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Term
| Which part of the lymph node is rich in B cells and macrophages? |
|
Definition
|
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Term
| What are germinal centers? |
|
Definition
Regions within follicles which develop in response to antigen stimulation
-made of rapidly dividing B cells & FDCs |
|
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Term
|
Definition
| follicular dendritic cells |
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Term
| GCs serve as sites for.... (5) |
|
Definition
-clonal expansion
-Ig class switching
-somatic mutation
-affinity maturation
-generation of memory B cells |
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Term
|
Definition
| region of LN rich in T cells, HEVs and APCs |
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Term
|
Definition
supply LN with APCs, lymphocytes, soluble antigens
drain the LN of lymphocytes |
|
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Term
| What is found within the medulla of LNs? (5) |
|
Definition
B cells
T cells
macrophages
plasma cells
memory T & B cells |
|
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Term
| How does lymph flow through the lymph ducts? |
|
Definition
| muscle contraction & 1-way valves to prevent backflow |
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Term
| Which chemokines draw APCs to the lymph node? What receptor do they bind to on APC? |
|
Definition
CCL19 & CCL21
bind to CCR7 |
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Term
| Describe the process of lymphocyte extravasation |
|
Definition
1. Lymphocytes drawn via CCL21 and CCL19 binding to CCR7
2. L-selectin CD62L interations with endothelial CD34 for tethering & rolling
3. Rolling induces expression of lymphocytes adhesion molecules
4. Adhesion molecules adhere to EC receptors
5. Lymphocytes are extravasated into LN |
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|
Term
| How are B cells drawn to follicles for interaction with APC? |
|
Definition
CCL19 & CCL21 via CCR7
CXCL13 via CXCR5
CXCL12 via CXCR4 |
|
|
Term
| How are T cells drawn to follicles? |
|
Definition
CCL19 & CCL21 via CCR7
CXCL12 via CXCR4 |
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Term
| What happens to lymphocytes after antigen specific T & B cells have been activated? |
|
Definition
| EC expresses S1P1 which binds to lymphocyte S1P receptors and allows them to be released from the LN |
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Term
| What happens to plasma cells after differentiation into antibody-secreting effector cells? |
|
Definition
-some go to medulla, secrete Ab into circulation
-some go to paracortex, enter efferent lymphatic / circulation, take up residence in BM equivalent tissues & spleen
-most undergo apoptosis
-ones that target immune-dominant epitopes will remain many years, secreting Ab for long-term immunity |
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|
Term
| How are memory B-cells able to survive long-term? |
|
Definition
FDCs secrete BAFF which promote B-cell survival
FDCs slowly release antigen overtime, essential for B cell survival |
|
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Term
| What happens during a secondary response to an antigen? |
|
Definition
-memory T cells in periphery are immediately activated by APCs
-migrate via afferent lymph to follicles
-interact with memory B cells to promote proliferation & differentiation into effector plasma cells |
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|
Term
| How is the porcine lymph node different from other mammals? |
|
Definition
-more similar to nodules than true lymph node
-afferent lymph duct in each nodule, surrounded by paracortex
-cortex surrounds paracortex, has 1 efferent duct (poor drainage of medulla)
-lymphocytes enter via HEV & afferent but leave primarily via HEV |
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Term
| What are the roles of the spleen (3) |
|
Definition
-storing RBCs & platelets
-recycling iron
-capturing blood borne antigens |
|
|
Term
| What are the two compartments of the spleen and what does each do? |
|
Definition
Red Pulp
-storing RBCs & recycling old ones
White Pulp
-PALS rich in T cells & follicles rich in B cells |
|
|
Term
| What happens after APC have presented antigen to specific T cells, activating B cells? |
|
Definition
| mature B cells (plasma cells) migrate to red pulp & release antibodies into the splenic vein |
|
|
Term
| Where does APC of blood-borne antigens typically occur? |
|
Definition
liver
spleen
bone marrow equivalent tissues |
|
|
Term
| Where does antigen presentation at mucosal surfaces typically occur? |
|
Definition
liver
spleen
bone marrow
also LN, Peyer's patches & tonsils |
|
|
Term
| Where does antigen presentation of skin antigens typically occur? |
|
Definition
in draining lymph nodes
(or nodules in chickens, lymphoid aggregates in fish) |
|
|
Term
| What organs produce antibodies during the mammalian primary immune response? |
|
Definition
| plasma cells within the spleen & lymph nodes |
|
|
Term
| What organs produce antibodies during the mammalian secondary immune response? |
|
Definition
| memory B cells in bone marrow equivalent tissues |
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