Term
| What are the 3 main types of true APCs? |
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Definition
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Term
| Which APCs are most efficient? Why? (2) |
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Definition
Dendritic Cells
-lots of adhesion & co-stimulatory molecules on surface
-no antimicrobial enzymes or ROS = can load more undegraded antigen onto MHC molecules |
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Term
| What makes B cells unique in terms of their APC ability? |
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Definition
| have BCRs (antigen receptors) |
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Term
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Definition
| allows B cells to respond to specific antigens |
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Term
| How do B cells handle T-dependent antigens? |
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Definition
| -rapidly process & present to antigen-specific T cell |
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Term
| How do B cells handle T-independent antigens? |
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Definition
| B cells are immediately activated, differentiate into plasma cells which secrete antibody |
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Term
| Are B cells more important during a primary or secondary immune response? |
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Definition
| secondary (due to development of memory B cells, Ig class switching, affinity maturation) |
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Term
| Do DCs have a role in regulating the immune response? |
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Definition
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Term
| What are the precursors for DCs? |
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Definition
lymphoid cells
myeloid precursor cells |
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Term
| Myeloid precursor cells can differentiate into ________ , _________ , or _______ depending on ________ |
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Definition
myeloid DCs (MDC)
FDC
Langerhangs cells (LC)
cytokines present in the area & interaction with surrounding cells |
|
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Term
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Definition
-secrete BAFF important for memory B cell survival
-Ig class switching within GCs of 2ndary lymphoid tissue |
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Term
| MDCs are able to induce differentiation of regulatory T cells in the presence of _____ and ____ |
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Definition
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Term
| Which myeloid sub-population is important for maintaining tolerance to self-antigens & commensal microbes in peripheral tissue? |
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Definition
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Term
| Which myeloid sub-population traps epidermal antigens? |
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Definition
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Term
| Lympoid DC precursors differentiate into _____ and then _____ |
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Definition
| plasmacytic cells and then plasmacytoid DCs (PDCs) |
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Term
| What do PDCs in the thymus do? |
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Definition
| present self-antigens to T cells during positive & negative T-cell selection |
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Term
| Where does positive selection of T cells occur? Which cells are selected? Why is this important? |
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Definition
in the thymic cortex
CD4+CD8+
ensures the surviving T cells can recognize MHC class I or class II molecules |
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Term
| What happens after CD4+CD8+ T cells have been selected? |
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Definition
differentiate into CD4+ OR CD8+
negative selection in thymic medulla to remove T cells which bind strongly to self-peptide |
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Term
| Where does negative selection take place? |
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Definition
|
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Term
| What happens to T cells which don't succeed in positive/negative selection? |
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Definition
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Term
| Peripheral PDCs are an important source of _____ and _____ |
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Definition
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Term
| Peripheral PDCs are involved in activating _____ cells which indicate they are involved in triggering the immune response to a viral infection |
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Definition
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Term
| Why are immature DCs not effective in carrying out antigen presentation? |
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Definition
| cell membrane doesn't have the key signaling & adhesion molecules |
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Term
| Immature DCs are very good at..... |
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Definition
| trapping & phagocytising particles & microbes |
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Term
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Definition
| as they travel from their resident tissue to secondary lymphoid tissues, drawn by CCL19 and CCL21 |
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Term
| Mature DCs express ______ which acts as an adhesion molecule with ______ an naive T-cells |
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Definition
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Term
| As DCs mature they secrete _____ which attracts T cells |
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Definition
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Term
| What are the 3 signals DCs provide to T cells |
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Definition
1. MHC-restrcted antigen presentation to TCR
2. Co-stimulatory signaling through DC CD40 and CD80/86 to T cell
3. Cytokine or receptor-mediated signaling to drive T cell polarization |
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Term
| DC1 cells secrete _____ which drive(s) Th1 cell differentiation favouring ____ |
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Definition
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Term
| DC2 cells secrete _____ which drive(s) Th2 cell differentiation favouring ____ |
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Definition
IL-1, IL-4, IL-6, IL-10
AbMIR |
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Term
| What do pigs and ruminants have instead of IL-4? |
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Definition
|
|
Term
| DC IL-23 supports differentiation of.... |
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Definition
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Term
| What determines DC 1 / 2 differentiation? |
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Definition
| PAMP & DAMP ligands and the cytokine mileau in surrounding tissue |
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Term
| TLR ___, ____, ___ and ___ promote DC1 cell differentiation |
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Definition
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Term
| DCs are mucosal surfaces preferentially secrete... |
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Definition
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Term
| Why are thymic PDCs unable to provide signals 2 & 3 to T cells? |
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Definition
| they are perpetually immature |
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Term
| What is required in order for phagocytic cells to be able to present exogenous antigens to activate Th-cells? |
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Definition
| must express MHC class II |
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Term
| Where are MHC Class II synthesized? |
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Definition
|
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Term
| What stabilizes the alpha and beta chains of the MHC while the molecule is being packaged? |
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Definition
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Term
|
Definition
| small peptide fragment remaining after the invariant chain of a lysosome is degraded |
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Term
| What happens when a lysosome molecule phagocytizes a particle? (3) |
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Definition
-CLIP is displaced by antigenic peptides
-phagolysosome is directed to cell surface
-MHC Class II molecules are expressed on cell mmb |
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Term
| What mediates the exchange of CLIP for an antigenic peptide? What regulates its activity? |
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Definition
non-classical MHC Class II molecule DM
DM is regulated by DO |
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Term
| What class of MHC is required to process endogenous antigens? |
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Definition
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Term
| Describe the processing that takes place for endogenous antigens |
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Definition
1. Ubiquitination
2. Processing within proteosome
3. Degradation & recycling of most peptides
3. Remaining peptides transported to ER via TAP1 & TAP2
4. Peptides loaded onto MHC class I
5. MHC class I released from ER, directed to cell surface to interat with Tc cell TCRs |
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Term
| What transporter proteins carry endogenous peptide fragments from the cytoplasm to the ER & load them onto MHC class I? |
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Definition
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Term
| How are MHC class I molecules assembled? |
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Definition
1. alpha chain & B2-microglobulin produced & assembled in RER & ER
2. Calnexin associates with alpha chain until it is replaced by B2 microgobulin
3. Celreticulun, tapasin, ERp57 associate in peptide-binding grove to increase stability |
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Term
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Definition
| when exogenous viral proteins are not completely degraded in phagoendosome, so end up being processed in proteosome & loaded onto Class I rather than Class II molecules |
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|
Term
| Are MHC molecule antigen-binding sites specific or non-specific? |
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Definition
| non-specific (degenerate) |
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