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Questions and Answers
What are the three major types of lymphocytes?
What are the three major types of lymphocytes?
T lymphocytes, B lymphocytes and Natural killer cells
What is the function of each lymphocyte?
What is the function of each lymphocyte?
T lymphocytes = Regulate adaptive immunity and are responsible for cell-mediated immune responses B lymphocytes = Antibody production NK cells = play a role in innate immunity (Large Granular lymphocytes) free bee = free bee
T cell development begins well before birth
T cell development begins well before birth
True
Where do pre-T cells migrate to complete their development after leaving the bone marrow?
Where do pre-T cells migrate to complete their development after leaving the bone marrow?
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Describe the development of the T cell (3 steps)
Describe the development of the T cell (3 steps)
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What characteristic allows T cells to recognize a wide variety of antigens?
What characteristic allows T cells to recognize a wide variety of antigens?
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Which gene segments are involved in encoding TCR components?
Which gene segments are involved in encoding TCR components?
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How does the specificity of a T cell response relate to the TCR and the antigen?
How does the specificity of a T cell response relate to the TCR and the antigen?
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What is meant by the term 'complementarity' in the context of antigens and TCRs?
What is meant by the term 'complementarity' in the context of antigens and TCRs?
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What distinguishes T cells and B cells in their ability to generate diversity in antigen recognition?
What distinguishes T cells and B cells in their ability to generate diversity in antigen recognition?
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What is the first step in TCR gene rearrangement?
What is the first step in TCR gene rearrangement?
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During TCR gene rearrangement, which segment is added last?
During TCR gene rearrangement, which segment is added last?
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Which sequence correctly represents the order of segments joined during the TCR beta chain rearrangement?
Which sequence correctly represents the order of segments joined during the TCR beta chain rearrangement?
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Which segment remains unexpressed until after TCR gene rearrangement is completed?
Which segment remains unexpressed until after TCR gene rearrangement is completed?
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What is the final configuration of the TCR beta chain before being expressed?
What is the final configuration of the TCR beta chain before being expressed?
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Which molecule on T cells interacts with B7 on dendritic cells to provide a necessary costimulatory signal for T cell activation?
Which molecule on T cells interacts with B7 on dendritic cells to provide a necessary costimulatory signal for T cell activation?
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A fully rearranged Beta chain is able to be expressed before the alpha chain has been rearranged
A fully rearranged Beta chain is able to be expressed before the alpha chain has been rearranged
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Which role do RAG1 and RAG2 play in TCR development?
Which role do RAG1 and RAG2 play in TCR development?
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What function does DNA-dependent protein kinase serve in the context of TCR development?
What function does DNA-dependent protein kinase serve in the context of TCR development?
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In the recombination process of TCR genes, what is the primary outcome of RAG1 and RAG2 cleavage?
In the recombination process of TCR genes, what is the primary outcome of RAG1 and RAG2 cleavage?
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How does the action of RAG1 and RAG2 influence the diversity of TCRs?
How does the action of RAG1 and RAG2 influence the diversity of TCRs?
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What is a primary consequence of the action of RAG1 and RAG2 in the context of TCR development?
What is a primary consequence of the action of RAG1 and RAG2 in the context of TCR development?
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The diversity of the TCR is primarily generated by which of the following processes?
The diversity of the TCR is primarily generated by which of the following processes?
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What does the T cell need in order to be of use?
What does the T cell need in order to be of use?
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What is the primary purpose of positive selection in T cell development?
What is the primary purpose of positive selection in T cell development?
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What percentage of thymocytes typically fails to pass positive selection?
What percentage of thymocytes typically fails to pass positive selection?
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Which of the following accurately describes a consequence of negative selection in T cell development?
Which of the following accurately describes a consequence of negative selection in T cell development?
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In which anatomical location does T cell selection primarily occur?
In which anatomical location does T cell selection primarily occur?
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What ability must a newly created TCR demonstrate to pass positive selection?
What ability must a newly created TCR demonstrate to pass positive selection?
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The T cells that survive both selections (positive and negative) are released into the __________
The T cells that survive both selections (positive and negative) are released into the __________
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Early stage thymocytes lack CD4 and CD8, they are _________ cells
Early stage thymocytes lack CD4 and CD8, they are _________ cells
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CD4 and CD8 are expressed once the alphabeta TCR is expressed- they become __________ T cells
CD4 and CD8 are expressed once the alphabeta TCR is expressed- they become __________ T cells
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Mature T cells are single positive, they express CD4 or CD8 only
Mature T cells are single positive, they express CD4 or CD8 only
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The ________ allows thymic epithelial cells to express many of the proteins usually found in other tissues of the body
The ________ allows thymic epithelial cells to express many of the proteins usually found in other tissues of the body
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What is the function of mature immunocompetent B lymphocytes in the immune response?
What is the function of mature immunocompetent B lymphocytes in the immune response?
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During which stage do B lymphocytes make contact with specific antigens?
During which stage do B lymphocytes make contact with specific antigens?
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What outcomes can activated B cells achieve after differentiation?
What outcomes can activated B cells achieve after differentiation?
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In which anatomical location do B lymphocytes primarily develop?
In which anatomical location do B lymphocytes primarily develop?
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Which step follows the activation phase in the B cell response to an antigen?
Which step follows the activation phase in the B cell response to an antigen?
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What is the primary location for B lymphocyte development after birth?
What is the primary location for B lymphocyte development after birth?
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Which of the following factors is essential for the differentiation of B lymphocyte precursor cells?
Which of the following factors is essential for the differentiation of B lymphocyte precursor cells?
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During which stage of B lymphocyte development do lymphoid precursor cells first begin to differentiate?
During which stage of B lymphocyte development do lymphoid precursor cells first begin to differentiate?
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Which structure serves as an initial site for B lymphocyte development during fetal life?
Which structure serves as an initial site for B lymphocyte development during fetal life?
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What is the initial developmental stage of B lymphocyte precursors referred to as?
What is the initial developmental stage of B lymphocyte precursors referred to as?
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The BCR has 2 heavy chains and 2 light chains. The heavy chain has all 3 gene segments and the light chain has all four gene segments
The BCR has 2 heavy chains and 2 light chains. The heavy chain has all 3 gene segments and the light chain has all four gene segments
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Which of the following statements correctly describes the structure of B cell receptor?
Which of the following statements correctly describes the structure of B cell receptor?
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Light chains are rearranged at the pre-B cell stage
Light chains are rearranged at the pre-B cell stage
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What are the other receptors on B cells? (Hint 3)
What are the other receptors on B cells? (Hint 3)
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What is the primary function of RAG1 and RAG2 in B cell development?
What is the primary function of RAG1 and RAG2 in B cell development?
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At which developmental stage do B cells first express membrane-bound IgM?
At which developmental stage do B cells first express membrane-bound IgM?
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What triggers the negative selection or clonal deletion of B cells?
What triggers the negative selection or clonal deletion of B cells?
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Which chains must be expressed for a B cell to achieve full maturity?
Which chains must be expressed for a B cell to achieve full maturity?
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What fate do most of the B cells produced in the bone marrow experience daily?
What fate do most of the B cells produced in the bone marrow experience daily?
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Because of the alleleic exclusion (of rearrangement of Ig genes), only one type of light chain can be expressed , this is (..)
Because of the alleleic exclusion (of rearrangement of Ig genes), only one type of light chain can be expressed , this is (..)
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Study Notes
T cell Receptor Specificity
- The specificity of a T cell response is determined by the interaction between the T cell receptor (TCR) and its specific antigen (epitope).
- One TCR is specific for one antigen (epitope).
T cell Receptor Diversity
- Despite the specific nature of TCR-antigen interactions, animals can respond to a vast array of antigens. This diversity is achieved through the random rearrangement of germline gene segments that encode the TCR components.
- The gene segments involved in TCR diversity include:
- Variable (V)
- Diversity (D)
- Joining (J)
- Constant (C)
- This unique mechanism of gene rearrangement is a key feature of T cells and B cells, enabling their adaptability to a wide range of pathogens.
T cell receptor (TCR) gene rearrangement: Beta chain
- The beta chain is the first chain of the TCR to undergo rearrangement.
- Rearrangement of the beta chain begins with the joining of the Dbeta and Jbeta gene segments.
- After Dbeta and Jbeta join, the Vbeta gene segment links with the DJbeta segment.
- Finally, the Cbeta gene segment joins with the DJVbeta segment.
- This complete DJVbetaCbeta segment is not yet expressed.
TCR Development
- Recombination activating genes RAG1 and RAG2 regulate TCR development.
- RAG1 and RAG2 function together to bring two regions of a gene together.
- RAG1 and RAG2 also cleave excess DNA to create diversity in the TCR repertoire.
- Enzymes like DNA-dependent protein kinase excise the intervening DNA, further contributing to TCR diversity.
T Cell Selection
- T cell selection occurs in the thymus.
- The selection process ensures that T cells can recognize and bind to MHC molecules.
- T cell selection occurs in two steps: positive selection and negative selection.
- Positive selection tests whether a newly created TCR can bind to MHC I or MHC II on thymic cortical epithelial cells (APCs).
- T cells must bind the MHC to pass positive selection.
- If the T cell does not bind the MHC, it fails positive selection and is eliminated via apoptosis.
- Positive selection eliminates thymocytes with failed TCR assembly or useless TCRs.
- If the TCR passes positive selection, the T cell is committed to either the CD4+ or CD8+ lineage.
- Approximately 96% of thymocytes fail positive selection and undergo apoptosis.
B Cell Development
- B cell development occurs in three stages: maturation, activation, and differentiation.
- Maturation refers to the generation of mature, immunocompetent B lymphocytes.
- Activation involves the contact of B lymphocytes with specific antigens.
- Differentiation leads to activated B cells becoming either plasma cells (producing antibodies) or memory B cells.
- For most vertebrates, including humans and mice, B lymphocyte development takes place in the bone marrow.
B Lymphocyte Development
- B lymphocyte development starts in fetal life and continues throughout life.
- Development occurs in the yolk sac, fetal liver, and bone marrow.
- After birth, B lymphocyte development only takes place in the bone marrow.
- B lymphocytes differentiate from lymphoid precursor cells into pro-B cells.
- Pro-B cells differentiate into B cell precursor cells with the help of interleukin-7 (IL-7) and bone marrow stromal cells.
B Cell Development
- B cell development begins in the bone marrow.
- The first genes to rearrange in pro-B cells are the heavy chain genes (D-J-V).
- Following the heavy chain rearrangement, the light chain genes (V-J) rearrange.
- Allelic exclusion ensures that only one type of light chain is expressed (either κ or λ).
- During the pre-B cell stage, immature B cells emerge.
- Immature B cells express membrane-bound IgM (mIgM) and Igα/Igβ chains, forming the B cell receptor (BCR) complex.
- The process of B cell receptor gene rearrangement is regulated by RAG1 and RAG2 recombinases.
- Immature B lymphocytes are not fully functional.
- Stimulation through the BCR in immature B cells can lead to cell death or anergy.
- Mature B cells express both membrane-bound IgM and IgD.
- B cells achieve full maturity through a change in RNA coding, allowing for the expression of both μ and δ heavy chains.
- Of the 5 x 10¹⁰ B cells produced daily in the bone marrow, only 10% reach circulation.
- The rest are eliminated through negative selection or clonal deletion to prevent autoimmunity.
- Negative selection eliminates B cells with high affinity for self-antigens.
- Mature B cells leave the bone marrow and enter the periphery.
- In the periphery, mature B cells undergo activation and differentiation into plasma cells.
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Description
Test your knowledge on the three major types of lymphocytes. This quiz covers key concepts about their roles, functions, and significance in the immune system. Ideal for biology students and enthusiasts looking to deepen their understanding of lymphocyte classification.
