PCB 3233: IMMUNOLOGY, EXAM 4
20Distinct0T-Cell0Lineages0-0ans✔a:b0&0g:d0(α:β0&0γ:δ)
Positive0Selection0-0ans✔leads0to0the0death0of0immature0T-
cells0having0receptors0that0do0not0interact0with0any0self-
MHC0I0or0II0(takes0place0prior0to0negative0selection)
Negative0Selection0-0ans✔induces0death0of0those0immature0T-
cells0that0are0autoreactive0(also0happens0with0B-cells)
Majority0Lineage0Type0of0T-Cell0-0ans✔a:b0(α:β095%)
Minority0Lineage0Type0of0T-Cell0-0ans✔g:d0(γ:δ05%)
What0is0another0word0for0immature0T-cell?0-0ans✔thymocyte
What0is0the0epithelial0cell0network0that0thymocytes0are0embedded0in0called?0-
0ans✔thymic0stroma
What0takes0place0in0the0Thymus0Cortex?0-0ans✔most0of0T-
cell0maturation0(except0negative0selection)
What0takes0place0in0the0Thymus0Medulla?0-0ans✔negative0selection0of0T-cells
What0do0macrophages0in0the0cortex0and0medulla0do?0-
0ans✔remove0thymocytes0that0fail0to0mature0properly
What0are0Hassall's0corpuscles?0-
0ans✔a0feature0of0the0medulla;0site0of0cell0destruction
What0is0DiGeorge0syndrome?0-
0ans✔deletion0of0chromosome022;0thymus0fails0to0develop
Progenitor0T-Cell0-
0ans✔lack0the0cell0surface0glycoproteins0(have0CD340surface0glycoprotein0of0stem0cell
s),0germline0configuration
, Double0Negative0Thymocyte0-
0ans✔at0the0start0of0gene0rearrangement;0no0CD40or0CD8
Double0Positive0Thymocyte0-
0ans✔after0rearrangement;0expresses0both0CD40and0CD8
Single0Positive0Thymocyte0-0ans✔after0positive0selection;0expresses0CD40or0CD8
IL-70Receptor0-0ans✔essential0for0binding0IL-
70secreted0by0thymic0stromal0cells;0helps0tell0the0cell0what0to0do0next
Notch-10-
0ans✔at0all0stages0of0maturation0in0the0thymus0signals0are0sent0to0this0receptor0to0dri
ve0the0T-cell0in0their0differentiation
How0many0chances0(per0chromosome)0does0the0B-
chain0have0to0rearrange0productivly?0-0ans✔2
What0does0a0successful0rearrangement0of0the0B-chain0induce?0-
0ans✔expression0of0CD40and0CD8
Allelic0Exclusion0of0B-chain0-0ans✔proliferation0initiated0by0signaling0is0repressed
What0signals0are0repressed0in0allelic0exclusion0of0the0B-chain?0-0ans✔pre-TCR,0RAG-
1,0RAG-2
When0does0rearrangement0of0the0a-chain0occur?0-0ans✔after0the0double-
positive0cells0stop0dividing
Will0most0developing0T-cell0be0able0to0make0a0productive0a-chain0rearrangement?0-
0ans✔yes
What0happens0after0the0first0rearrangement0between0V0and0J0segments0on0the0a-
chain?0-0ans✔d0(δ)0segment0is0deleted
What0is0the0first0checkpoint0of0a:b0(α:β)0chain0rearrangement?0-0ans✔once0a0b-
chain0is0produced0it0is0sent0to0the0ER0to0make0sure0it0can0bind0to0the0surrogate0a-
chain0(pTα)
What0is0the0second0checkpoint0of0a:b0(α:β)0chain0rearrangement?0-0ans✔once0an0a-
chain0is0made0it0is0sent0to0the0ER0to0make0sure0it0can0bind0to0the0b-chain
How0many0MHC0molecules0does0an0individual0express?0-0ans✔120(60MHC-
I0and060MHC-II)
What0percentage0of0a:b0(α:β)0TCRs0will0pass0positive0selection?0-0ans✔1-2%
20Distinct0T-Cell0Lineages0-0ans✔a:b0&0g:d0(α:β0&0γ:δ)
Positive0Selection0-0ans✔leads0to0the0death0of0immature0T-
cells0having0receptors0that0do0not0interact0with0any0self-
MHC0I0or0II0(takes0place0prior0to0negative0selection)
Negative0Selection0-0ans✔induces0death0of0those0immature0T-
cells0that0are0autoreactive0(also0happens0with0B-cells)
Majority0Lineage0Type0of0T-Cell0-0ans✔a:b0(α:β095%)
Minority0Lineage0Type0of0T-Cell0-0ans✔g:d0(γ:δ05%)
What0is0another0word0for0immature0T-cell?0-0ans✔thymocyte
What0is0the0epithelial0cell0network0that0thymocytes0are0embedded0in0called?0-
0ans✔thymic0stroma
What0takes0place0in0the0Thymus0Cortex?0-0ans✔most0of0T-
cell0maturation0(except0negative0selection)
What0takes0place0in0the0Thymus0Medulla?0-0ans✔negative0selection0of0T-cells
What0do0macrophages0in0the0cortex0and0medulla0do?0-
0ans✔remove0thymocytes0that0fail0to0mature0properly
What0are0Hassall's0corpuscles?0-
0ans✔a0feature0of0the0medulla;0site0of0cell0destruction
What0is0DiGeorge0syndrome?0-
0ans✔deletion0of0chromosome022;0thymus0fails0to0develop
Progenitor0T-Cell0-
0ans✔lack0the0cell0surface0glycoproteins0(have0CD340surface0glycoprotein0of0stem0cell
s),0germline0configuration
, Double0Negative0Thymocyte0-
0ans✔at0the0start0of0gene0rearrangement;0no0CD40or0CD8
Double0Positive0Thymocyte0-
0ans✔after0rearrangement;0expresses0both0CD40and0CD8
Single0Positive0Thymocyte0-0ans✔after0positive0selection;0expresses0CD40or0CD8
IL-70Receptor0-0ans✔essential0for0binding0IL-
70secreted0by0thymic0stromal0cells;0helps0tell0the0cell0what0to0do0next
Notch-10-
0ans✔at0all0stages0of0maturation0in0the0thymus0signals0are0sent0to0this0receptor0to0dri
ve0the0T-cell0in0their0differentiation
How0many0chances0(per0chromosome)0does0the0B-
chain0have0to0rearrange0productivly?0-0ans✔2
What0does0a0successful0rearrangement0of0the0B-chain0induce?0-
0ans✔expression0of0CD40and0CD8
Allelic0Exclusion0of0B-chain0-0ans✔proliferation0initiated0by0signaling0is0repressed
What0signals0are0repressed0in0allelic0exclusion0of0the0B-chain?0-0ans✔pre-TCR,0RAG-
1,0RAG-2
When0does0rearrangement0of0the0a-chain0occur?0-0ans✔after0the0double-
positive0cells0stop0dividing
Will0most0developing0T-cell0be0able0to0make0a0productive0a-chain0rearrangement?0-
0ans✔yes
What0happens0after0the0first0rearrangement0between0V0and0J0segments0on0the0a-
chain?0-0ans✔d0(δ)0segment0is0deleted
What0is0the0first0checkpoint0of0a:b0(α:β)0chain0rearrangement?0-0ans✔once0a0b-
chain0is0produced0it0is0sent0to0the0ER0to0make0sure0it0can0bind0to0the0surrogate0a-
chain0(pTα)
What0is0the0second0checkpoint0of0a:b0(α:β)0chain0rearrangement?0-0ans✔once0an0a-
chain0is0made0it0is0sent0to0the0ER0to0make0sure0it0can0bind0to0the0b-chain
How0many0MHC0molecules0does0an0individual0express?0-0ans✔120(60MHC-
I0and060MHC-II)
What0percentage0of0a:b0(α:β)0TCRs0will0pass0positive0selection?0-0ans✔1-2%
