Download Immunology Exam 4 Review: Questions and Answers (2026/2027 Update) and more Exercises Biology in PDF only on Docsity!
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Grade A
2 Distinct T-Cell Lineages a:b & g:d (α:β & γ:δ) Positive Selection 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 induces death of those immature T-cells that are autoreactive (also happens with B-cells) Majority Lineage Type of T-Cell a:b (α:β 95%) Minority Lineage Type of T-Cell g:d (γ:δ 5%)
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Grade A
What is another word for immature T-cell? thymocyte What is the epithelial cell network that thymocytes are embedded in called? thymic stroma What takes place in the Thymus Cortex? most of T-cell maturation (except negative selection) What takes place in the Thymus Medulla? negative selection of T-cells What do macrophages in the cortex and medulla do? remove thymocytes that fail to mature properly What are Hassall's corpuscles? a feature of the medulla; site of cell destruction
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Grade A
IL-7 Receptor essential for binding IL-7 secreted by thymic stromal cells; helps tell the cell what to do next Notch- 1 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? 2 What does a successful rearrangement of the B-chain induce? expression of CD4 and CD Allelic Exclusion of B-chain proliferation initiated by signaling is repressed What signals are repressed in allelic exclusion of the B-chain? pre-TCR, RAG-1, RAG- 2
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Grade A
When does rearrangement of the a-chain occur? after the double-positive cells stop dividing Will most developing T-cell be able to make a productive a-chain rearrangement? yes What happens after the first rearrangement between V and J segments on the a-chain? d (δ) segment is deleted What is the first checkpoint of a:b (α:β) chain rearrangement? 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? once an a-chain is made it is sent to the ER to make sure it can bind to the b-chain
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Grade A
What recognizes MHC in positive selection? CDR1 and CDR What recognizes peptides in positive selection? CDR How does the expression of CD4 and CD8 change during positive selection? goes from expressing both to expressing one What is the mediator of positive selection? cortical epithelial cells What percentage of a:b (α:β) TCRs will try a second a-chain arrangement during positive selection? 50%
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Grade A
What might a cell do if its first a-chain is rejected during positive selection? try a second arrangement What effector T-cell will a thymocyte become if it recognized MHC-1? CD What effector T-cell will a thymocyte become if it recognizes MHC-2? CD What does negative selection test? to see if self-peptide and MHC are recognized too strongly Where does negative selection take place? medulla What does AIRE stand for? autoimmune regulator
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Grade A
What happens to T-cells that survive the selection process? they become mature naive T-cells that become effector T-cells Where do T-cells go after the selection process? stay in the lymphoid tissues or migrate of sites of infection Where do T-cells come from before they mature in the thymus? bone marrow How do the T-cells get from the bone marrow to the thymus? bloodstream Is the thymus a primary or secondary lymphoid tissue? primary Where do naive T-cells activate/mature? secondary lymphoid tissues
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Grade A
Mature T-cells migrate from the thymus to the secondary lymphoid tissues via _______? the bloodstream What gene segments are rearranged for the a-chain? V and J What gene segments are rearranged for the b-chain? V, D, and J Is the a-chain similar to the heavy or light chain of the B-cell? light Is the b-chain similar to the heavy or light chain of the B-cell? heavy
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Grade A
Does DiGeorge's syndrome effect B-cells? yes In what part of somatic recombination are RAG-1 and RAG-2 important? allelic exclusion 12/23 (1/2 turn) Rule ensures that gene segments are joined in the correct order Without antigen stimulation, how long can a T-cell circulate in the body? years How many peptides can an MHC present? 10,
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Grade A
Why does B usually win against γ:δ? because it is one chain and g:d is two When in the maturation process is the cell considered double positive? after b-chain rearrangement When in the maturation process is the cell considered single positive? after positive selection What cells mediate negative selection? dendritic cells, macrophages, medullary epithelial cells Why don't g:d (γ:δ) cells need to undergo positive selection? they don't need MHC to present peptide Does the thymus play a role in the activation of naive T-cells? no
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Grade A
Where do dendritic cells settle in the secondary lymphoid tissues? T-cell area What cells can activate naive T-cells? dendritic cells (they are the only ones strong enough) Where does central tolerance take place? primary lymphoid tissue (thymus for T-cells; bone marrow for B-cells) Are T-reg CD4 or CD8 T-cells? CD What transcription factor is unique to T-reg cells? FoxP Are dendritic cells migatory cells? yes
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Grade A
Mature Naive T-Cell t-cell that has undergone somatic recombinant (gene rearrangement) & has a functional TCR on its surface; it just hasn't been activated yet What does HEV stand for? high endothelial venules What is a lymphocyte? subclass of leukocyte; T-cells, B-cells, NK-cells What is a leukocyte? white blood cell Where is AIRE located? medulla of the thymus
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Grade A
What do vascular addressins bind to? selectins What do integrins bind to? Ig superfamily proteins What do Ig superfamily proteins bind to? integrins What are some examples of vascular addressins? GlyCAM-1, CD34, MADCAM- 1 What is an example of a selectin? L-selectin
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Grade A
What is an example of an Ig superfamily protein? I-CAM What is an example of an integrin? LFA- 1 What are the steps of the homing process? rolling adhesion, tight binding, diapedesis, migration Diapedesis the passage of blood cells through the intact walls of the capillaries (HEV) How does a naive T-cell enter a lymph node? bloodstream through a HEV How does a T-cell leave a lymph node? bloodstream or efferent lymphatic
