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27 Cards in this Set
- Front
- Back
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What are the 2 main checks that must be crossed during lymphocyte maturation? Where does maturation occur
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Express an antigen receptor
Be nonreactive to self antigens. Primary lymphoid tissue(Thymus or Bone marrow) |
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How are variable domains created in BCR and TCR? What does this create?
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somatic recombination, creates variable antigen binding sites that are specific to one antigen
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How do the structures of TCR differ from BCR?
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BCR's are the same as IgM. 2 identical heavy and 2 identical light chains
TCR only have one alpha and one beta chains |
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What are the 4 stages of B-cell maturation?
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Progenitor B cell
Precursor B cell Immature B cell Mature B cell |
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What are the surface structure expressed at each stage of B cell maturation?
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Pro B= CD19 and CD10
Pre B cell= Ig heavy chain sucessfully rearranged and on surface with temp L chain Immature B cell-H and L chains both rearranged, expression of membrane IgM, negative selection and release from primary tissue Mature B- expression of both IgM and IgD |
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What proteins are expressed in the surrogate light chains?
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λ5 and VpreB and Igα\Igβ
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What is the differenct between surrogate light chains and mature light chains?
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they are invariant
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What does expression of the pre BCR allow to happen?
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Continued survival and prolif
Prevents 2nd heavy chain from undergoing recombination(if 1st sucessful) Stimulates L chain recombination Inhibits synthesis of surrogate L chain |
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Define negative selection?
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When B cells that strongly respond to self antigens are destroyed via apoptosis
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Do all pre-b-cells that respond to self antigens undergo apoptosis?
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No they can undergo light chain editing
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What happens during light chain editing?
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Light chain is rearranged with a different light chain allele to try and make a non self reactive BCR. if sucessful it excapes neg selec
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What are the stages of T cell maturation?
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Pro T cell
Pre T cell Double positive T cell Single Positive T cell Mature T cell |
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What occurs at each stage of T cell maturation?
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Pro T- Prolif and expression of CD25 and CD44, initiation of som. recom. of β chain
Pre T- Expression of β chain with surrogate α on surface=pTα and CD3+ζ Double Pos: CD4 and CD8, α rearrangment with β, positive and negative sel Single positive- down regulation of either CD4 or CD8 Mature T-release to circulation |
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What is included in the pre-T cell complex?
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rearranged B with surrogate a and CD3+ζ
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What does expression of the pre t cell complex allow?
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survivial and proliferation
prevents second B chain from having recombination stimulation of a recombination Stimulation of CD4\8 synth Inhibits synth of pTa |
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What are the 3 types of selection that T cells undergo?
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Positive: Cells survive if has weak response to MHC w\ self antigen(recognize MHC not antigen)
Negative selection: strong recognition of MHC\self antigen "Death by neglect"-no response = apoptosis |
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What happens if a cell is positively selected?
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CD4 or 8 is downregulated and it survives
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What is the difference in VDJ joining between B and T cells in prelymphocyte stage?
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B cell join DJ then do VDJ joining
T cells to VJ joining only V------D------J |
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What undergoes VDJ recombination in B cells vs T cells?
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B cell have Heavy chain recombination
T cells have B chain recombination |
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What happens(generally) during the pro lymphocyte stage of maturation?
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H(b cells) and B(T cells) chains have recombination and early markers are expressed
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What are the 3 types of selection that T cells undergo?
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Positive: Cells survive if has weak response to MHC w\ self antigen(recognize MHC not antigen)
Negative selection: strong recognition of MHC\self antigen "Death by neglect"-no response = apoptosis |
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What happens if a cell is positively selected?
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CD4 or 8 is downregulated and it survives
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What is the difference in VDJ joining between B and T cells in prelymphocyte stage?
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B cell join DJ then do VDJ joining
T cells to VJ joining only V------D------J |
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What undergoes VDJ recombination in B cells vs T cells?
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B cell have Heavy chain recombination
T cells have B chain recombination |
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What happens(generally) during the pre lymphocyte stage of maturation?
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H(b cells) and B(T cells) chains have recombination and early markers are expressed
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What happens in a general sense during pre lymphocyte stage?
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H or B chains expressed with surrogate L of a chains and initiation of VJ recombination of L and a, expression of pre-antigen receptor
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What happens in a general sense at the immature lymphocyte stage?
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Expression of complete antigen and selection:
Negative only for B Negative and POsitive for T |
