Term
| What are the three genes for class I and class II MHC in humans? for mice? |
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Definition
Humans
Class I: HLA-A, HLA-B, HLA-C
Class II: HLA-DR, HLA-DQ, HLA-DP
Mice
Class I: H-2 K, H-2 D, H-2 L
Class II: H-2 I-A, H-2 I-E
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Term
| What size are peptides that are bound to MHC I molecules? |
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Definition
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Term
| What size are peptides that are bound to MHC II molecules? |
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Definition
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Term
| True or false. MHC I is composed of two non-covalently linked chains, an MHC encoded alpha-chain and a non-MHC encoded Beta2-microglobulin. |
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Definition
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Term
| List 5 cells that are antigen-presenting cells (APCs). |
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Definition
Dendritic Cells
Macrophages
B cells
Activated T cells
Thymic epithelial cells |
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Term
| Which chromosomes code for the HLA region and the Beta-2 microglobulin of MHC Class I? |
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Definition
HLA - Chromosome 6 (short arm)
Beta-2 - Chromosome 15 |
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Term
| What is TAP and why is it important? |
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Definition
TAP = Transporter associated with Antigen Processing
TAP transports peptides from the cytosol into the ER, so they can be loaded onto MHC I molecules.
NOTE: TAP1 and TAP2 are encoded on class II MHC regions on chromosome 6. |
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Term
| What is the difference between direct and indirect allorecognition? |
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Definition
Direct: Recipient T-cell sees donor MHC as foreign antigen
T cell sees "Allogenic MHC + peptide"
Indirect: Allogeneic MHC taken up and processed by self APC
T cell sees "Self MHC + Foreign Peptide" |
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Term
| Contrast between the types of antigens T cells and B cells recognize. |
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Definition
T cells - mainly just proteins, only linear determinants
- can only recognize antigens bound to MHC
B cells - proetins, nucleic acids, polysaccharides, lipids and small molecules; conformational and linear determinants |
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Term
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Definition
| T cell can only recognize and respond to peptides presented on a self-MHC. |
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Term
| True or false: B cells are the main cells acting in a primary immune response. |
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Definition
| False. B cells are not efficient in the primary immune response because antigen-specific B cells are present at very low frequency and have low expression of costimulatory molecules. |
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Term
| What is the most efficient APC for a primary response? secondary response? |
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Definition
Primary response - Dendritic Cell (deliver signal and activate naive T cells)
Secondary response - B cells (quick clonal expansion in secondary response) |
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Term
| Why is there an HLA-DM? HLA-DO? |
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Definition
HLA-DM is a non-classical HLA, found in MIIC (a cellular compartment), which catalyze the exchange of CLIP from the MHC II with antigenic peptides 13-18 residues in length.
HLA-DO inhibits HLA-DM. It is expressed only by the thymic and B cells. |
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Term
| What chaperone molecules are required for the assembly of MHC I? |
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Definition
1) Calnexin - promotes folding of alpha-chain so beta2-microglobulin can associated
2) Tapasin - brings TAP transporter close to MHC I
3) Calreticuli - associated with MHC I
4) ERp57 - stabilizes whole structure
All three stabili |
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Term
| Which cells can cross-present? |
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Definition
| Dendritic cells. Cross-presentation allows DCs to provide appropriate signals to CTL without having to be infected by a given pathogen |
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Term
| What is CD1? Where is it expressed? What is its purpose? |
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Definition
CD1 is a non-polymorphic MHC-like molecules.
Expressed on dendritic cells.
Function: present lipids/glycolipids (mycolic acids/lipoarabinomannan) from mycobacteria to gamma/delta T cells and NK cells. |
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Term
| What are superantigens and why are they bad? What microbes can utilize superantigens? |
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Definition
Superantigens bind outside peptide-binding site
--> simultaneously binds TCR and alpha-chain of MHC II (cross-linkaage)
--> non-specific activation of T cells (massive TH response).
--> systemic toxicity and deletion/anergy of host cells due to overstimulation
Superantigens used by - gram+ bacteria, staphylococcal enterotoxins, TSS toxin |
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