PCB 3233 IMMUNOLOGY – EXAM 4 QUESTIONS AND ANSWERS (100% VERIFIED)
| UNIVERSITY-LEVEL STUDY MATERIAL
2 Distinct T-Cell Lineages -
Answer-a:b & g:d (α:β & γ:δ)
Positive Selection -
Answer-leads to the death of immature T-cells having receptors that do not interact with
any self-MHC I or II (takes place prior to negative selection)
Negative Selection -
Answer-induces death of those immature T-cells that are autoreactive (also happens with
B-cells)
Majority Lineage Type of T-Cell -
Answer-a:b (α:β 95%)
Minority Lineage Type of T-Cell -
Answer-g:d (γ:δ 5%)
What is another word for immature T-cell? -
Answer-thymocyte
What is the epithelial cell network that thymocytes are embedded in called? -
Answer-thymic stroma
What takes place in the Thymus Cortex? -
Answer-most of T-cell maturation (except negative selection)
What takes place in the Thymus Medulla? -
Answer-negative selection of T-cells
What do macrophages in the cortex and medulla do? -
Answer-remove thymocytes that fail to mature properly
What are Hassall's corpuscles? -
Answer-a feature of the medulla; site of cell destruction
What is DiGeorge syndrome? -
Answer-deletion of chromosome 22; thymus fails to develop
Progenitor T-Cell -
Answer-lack the cell surface glycoproteins (have CD34 surface glycoprotein of stem
cells), germline configuration
Double Negative Thymocyte -
,Answer-at the start of gene rearrangement; no CD4 or CD8
Double Positive Thymocyte -
Answer-after rearrangement; expresses both CD4 and CD8
Single Positive Thymocyte -
Answer-after positive selection; expresses CD4 or CD8
, IL-7 Receptor -
Answer-essential for binding IL-7 secreted by thymic stromal cells; helps tell the cell what
to do next
Notch-1 -
Answer-at all stages of maturation in the thymus signals are sent to this receptor to drive
the T-cell in their differentiation
How many chances (per chromosome) does the B-chain have to rearrange
productivly?
-
Answer-2
What does a successful rearrangement of the B-chain induce? -
Answer-expression of CD4 and CD8
Allelic Exclusion of B-chain -
Answer-proliferation initiated by signaling is repressed
What signals are repressed in allelic exclusion of the B-chain? -
Answer-pre-TCR, RAG-1, RAG-2
When does rearrangement of the a-chain occur? -
Answer-after the double-positive cells stop dividing
Will most developing T-cell be able to make a productive a-chain rearrangement?
-
Answer-yes
What happens after the first rearrangement between V and J segments on the a-
chain?
-
Answer-d (δ) segment is deleted
What is the first checkpoint of a:b (α:β) chain rearrangement? -
Answer-once a b- chain is produced it is sent to the ER to make sure it can bind to the
surrogate a-chain (pTα)
What is the second checkpoint of a:b (α:β) chain rearrangement? -
Answer-once an a- chain is made it is sent to the ER to make sure it can bind to the b-
chain
How many MHC molecules does an individual express? -
Answer-12 (6 MHC-I and 6 MHC-II)
What percentage of a:b (α:β) TCRs will pass positive selection? -
Answer-1-2%
| UNIVERSITY-LEVEL STUDY MATERIAL
2 Distinct T-Cell Lineages -
Answer-a:b & g:d (α:β & γ:δ)
Positive Selection -
Answer-leads to the death of immature T-cells having receptors that do not interact with
any self-MHC I or II (takes place prior to negative selection)
Negative Selection -
Answer-induces death of those immature T-cells that are autoreactive (also happens with
B-cells)
Majority Lineage Type of T-Cell -
Answer-a:b (α:β 95%)
Minority Lineage Type of T-Cell -
Answer-g:d (γ:δ 5%)
What is another word for immature T-cell? -
Answer-thymocyte
What is the epithelial cell network that thymocytes are embedded in called? -
Answer-thymic stroma
What takes place in the Thymus Cortex? -
Answer-most of T-cell maturation (except negative selection)
What takes place in the Thymus Medulla? -
Answer-negative selection of T-cells
What do macrophages in the cortex and medulla do? -
Answer-remove thymocytes that fail to mature properly
What are Hassall's corpuscles? -
Answer-a feature of the medulla; site of cell destruction
What is DiGeorge syndrome? -
Answer-deletion of chromosome 22; thymus fails to develop
Progenitor T-Cell -
Answer-lack the cell surface glycoproteins (have CD34 surface glycoprotein of stem
cells), germline configuration
Double Negative Thymocyte -
,Answer-at the start of gene rearrangement; no CD4 or CD8
Double Positive Thymocyte -
Answer-after rearrangement; expresses both CD4 and CD8
Single Positive Thymocyte -
Answer-after positive selection; expresses CD4 or CD8
, IL-7 Receptor -
Answer-essential for binding IL-7 secreted by thymic stromal cells; helps tell the cell what
to do next
Notch-1 -
Answer-at all stages of maturation in the thymus signals are sent to this receptor to drive
the T-cell in their differentiation
How many chances (per chromosome) does the B-chain have to rearrange
productivly?
-
Answer-2
What does a successful rearrangement of the B-chain induce? -
Answer-expression of CD4 and CD8
Allelic Exclusion of B-chain -
Answer-proliferation initiated by signaling is repressed
What signals are repressed in allelic exclusion of the B-chain? -
Answer-pre-TCR, RAG-1, RAG-2
When does rearrangement of the a-chain occur? -
Answer-after the double-positive cells stop dividing
Will most developing T-cell be able to make a productive a-chain rearrangement?
-
Answer-yes
What happens after the first rearrangement between V and J segments on the a-
chain?
-
Answer-d (δ) segment is deleted
What is the first checkpoint of a:b (α:β) chain rearrangement? -
Answer-once a b- chain is produced it is sent to the ER to make sure it can bind to the
surrogate a-chain (pTα)
What is the second checkpoint of a:b (α:β) chain rearrangement? -
Answer-once an a- chain is made it is sent to the ER to make sure it can bind to the b-
chain
How many MHC molecules does an individual express? -
Answer-12 (6 MHC-I and 6 MHC-II)
What percentage of a:b (α:β) TCRs will pass positive selection? -
Answer-1-2%
