CMB2004 2

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  • Created by: Ezz96
  • Created on: 23-01-17 21:05
B cell development
Develop in a continuous process from haematopoietic stem cells in bone marrow that express PAX5 transcription factor. Involves rearrangement and expression of Ig genes
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Pre- B cell receptor
Delivers signal to pre-B cell: no AG required. Signal turns OFF RAG-1, RAG-2 genes and 5/6 rounds of division occur. Surrogate light chain expression stops. RAG-1 and RAG-2 turn ON. L chain rearrangement starts. (RAG genes needed for gene rearrange)
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What happens if immature B cells bind multivalent self-antigen
Clonal deletion and apoptosis or receptor editing: further light chain gene rearrangements of variable regions (Second chance)
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What happens if immature B cell binds soluble self-antigen
Cell becomes unresponsive (anergic)
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T cell development
Originate from bone marrow stem cells, rearrange receptor genes, express pre-T receptor, elimination of self-reactive T cells, negative selection but undergo development in thymus and must be able to interact with self MHC but not too strongly
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T cell development in the thymus
After precursors produced in the bone marrow, migrate to thymus. Then: 1. Rearrange TCR genes (beta chain first, expressed along with pre-Ta then a) and express TCR 2.Acquire other markers eg CD3, CD4, CD8. 3.Undergo positive and negative selection
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The thymus
Bi-lobed organ in anterior mediastinum. Each lobe divided into many lobules with an outer cortex and inner medulla. Cells: lymphoid cells, epithelial cells, macrophages and dendritic cells.
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TCR complex
Expression of TCR requires CD3 complex, LOOK UP pg 6
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TCR before fine tuning
1) can recognise and respond to self MHC plus foreign peptide WANT. 2. can recognise and respond to self MHC plus self peptide (remove by positive selection and move to medul) 3.No recognition of self-MHC (removed by negative selection and apoptosis)
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If recognise peptide + Class 1:
lose CD4 T cells
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If recognise peptide + Class II:
lose CD8 T cells
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TCR/p/MHC affinity is basis for selection:
All T cells recognising self MHC/self peptide are positively selected, those with the highest affinity TCR are then negatively selected.
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GOAL
A population of T cells with low affinity for self peptide + self MHC but high affinity for foreign peptide + self MHC
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CD4 and CD8
CD4 - Class II CD8 - Class II
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Other cards in this set

Card 2

Front

Pre- B cell receptor

Back

Delivers signal to pre-B cell: no AG required. Signal turns OFF RAG-1, RAG-2 genes and 5/6 rounds of division occur. Surrogate light chain expression stops. RAG-1 and RAG-2 turn ON. L chain rearrangement starts. (RAG genes needed for gene rearrange)

Card 3

Front

What happens if immature B cells bind multivalent self-antigen

Back

Preview of the front of card 3

Card 4

Front

What happens if immature B cell binds soluble self-antigen

Back

Preview of the front of card 4

Card 5

Front

T cell development

Back

Preview of the front of card 5
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