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16 Cards in this Set
- Front
- Back
7.1
MHC |
- cell communicate to the immune system about antigens that they have encountered
- rejection of tissue grafts |
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7.2
human leukocyte antigen (HLA) |
MHC protein in human
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7.3
MHC Class II molecules |
- HLA-DR, HLA-DQ, HLA-DP in humans
- surface of cells of the immune system - Eg, B lymphocytes, dendritic cells, macrophages, activated T cells (human) - inducible on some other cell types - once expressed, cell becomes visible to CD4+ class II-specific T cells |
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7.4
MHC Class I molecules |
- HLA-A, HLA-B, HLA-C in humans
- surface of essentially all nucleated cells - Make cells 'visible' to circulating CD8+ class I-specific T lymphocytes |
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7.5
MHC II structure |
- 2 chain molecules
- alpha and beta chain - extracellular portion: alpha 1 and alpha 2, beta 1 and beta 2 - antigen binding groove = alpha 1 + beta 1 |
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7.6
MHC I structure: |
- 2 chain molecules
- alpha (heavy) chain + smaller polypeptide, beta 2 microglobulin - alpha chain is inserted in the cell membrane - external: alpha 1 (N terminal), alpha 2 and alpha 3 alpha 3 and beta 2m form a platform - on top = antigen binding groove formed by alpha 1 and alpha 2 |
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7.7
MHC I assembly: |
- assembled in ER
- picks up a peptide (2000 different kinds) - peptides are derive from normal degradation of cellular proteins or pathogens |
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7.8
MHC II assembly: |
- assembled in ER
- picks up a peptide (2000 different kinds) - peptides are derived from normal degradation of cellular proteins or pathogens |
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7.9
MHC II assembly: |
- associate w/ a 3rd polypeptide chain in the ER, the invariant chain
- chain blocks peptide binding groove and target MHC II to the endocytic pathway - once in this pathway, invariant chain is removed - MHC II is free to bind peptides (same kind as in MHC I) - after stabilized by bound peptide -> MHC II moves to the cell a surface and interacts w/ T lymphocytes |
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7.10
Major Histocompatibility Complex (MHC) Chromosome: |
6
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7.11
Fibroblasts: |
express only MHC I
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7.12
T Cell Receptor for Antigen |
- inserted in the T cell surface, never secreted
- 2 polypeptide chains, alpha, beta - S-S bond - CD3 |
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7.13
Recognition of Antigenic Peptide-MHC Complexes by TCR |
- self peptides are ignored b/c T cells w/ TCR to self are negatively selected in the thymus
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7.14
T cell signaling and adhesion molecules |
- TCR ligand affinity low
- TCR cytoplasmic tails short - TCR needs help from other molecules - CD3, CD4, CD8, LFA1 (adhesion molecule) |
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7.15
TCR antigen recognition |
- variable region N-terminal
- constant region - approx. 30000 clonally unique TCR/cell |
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7.16
TCR Dual recognition: |
- TCR that is specific for a particular MHC-peptide complex is specific for both antigen peptide (Ag restricted) and MHC (MHC restricted)
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