TCR Gene Rearrangement and Organization

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Questions and Answers

What is the configuration of the TCR genes in the earliest cell entering the thymus?

  • Unrearranged
  • Partially rearranged
  • Completely rearranged
  • Rearranged (correct)

What is the order of gene rearrangement if the γ chain genes rearrange successfully?

  • α gene rearrangement then δ chain genes
  • β gene rearrangement then δ chain genes
  • δ chain genes then α gene rearrangement
  • δ chain genes then β gene rearrangement (correct)

What is the role of recombination activation genes (RAGs) in T cells?

  • To generate TCR diversity
  • To inhibit the recombinase gene
  • To activate the recombinase gene (correct)
  • To regulate the allelic exclusion

What is the approximate number of different TCR structures that can be generated from αβ and γδ TCRs?

<p>10^13 (D)</p> Signup and view all the answers

What is the process called when no further gene rearrangements occur after successful gene rearrangements?

<p>Allelic exclusion (D)</p> Signup and view all the answers

What happens if all the gene rearrangements are unsuccessful?

<p>The second copy of genes on respective chromosomes will begin the rearrangement process (D)</p> Signup and view all the answers

What is the function of RAG-1 and RAG-2 genes in the process of recombination?

<p>To recognize specific DNA signal sequences (C)</p> Signup and view all the answers

What is the difference between immuneoglobulin genes and genes encoding TCR?

<p>Immunoglobulin genes do not undergo somatic mutation (A)</p> Signup and view all the answers

Where do T lymphocytes develop?

<p>In the thymus (B)</p> Signup and view all the answers

What is the function of positive selection in the thymus?

<p>To allow TCRs to recognize MHC molecules (C)</p> Signup and view all the answers

What is the outcome of TCRs binding too strongly to p-MHC in the thymus?

<p>Negative selection and elimination (A)</p> Signup and view all the answers

What is the outcome of a defect in RAG-1 or RAG-2 genes?

<p>Severe combined immunodeficiency (SCID) (C)</p> Signup and view all the answers

What is the name of the cells that do not express either the CD4 or CD8 co-receptor?

<p>Double-negative cells (D)</p> Signup and view all the answers

At what stage do the cells decide to become δγ or αβ T cells?

<p>At the double-negative stage (B)</p> Signup and view all the answers

What percentage of thymocytes never become fully functional and die in the thymus?

<p>96%-98% (D)</p> Signup and view all the answers

What is the result of positive selection?

<p>Down-regulation of RAG1 and RAG2 gene expression (A)</p> Signup and view all the answers

What is the function of negative selection?

<p>To remove T cells that express TCR with high reactivity to self components (B)</p> Signup and view all the answers

What type of molecule is associated with the TCR β chain on the surface of pre-T cells?

<p>Invariant pre-Tα molecule (B)</p> Signup and view all the answers

What type of T-cells are MHC II restricted and recognize specific foreign peptides only when presented in association with specific MHC II molecules?

<p>CD4 T-cells (B)</p> Signup and view all the answers

Which type of T-cells produces cytokines of CMI and inflammation?

<p>Th1 T-cells (D)</p> Signup and view all the answers

What is the primary function of CD4 T-cells when recognizing antigen on the surface of APC?

<p>Secreting cytokines (C)</p> Signup and view all the answers

What is the term for the process by which T-cells that are unable to bind to MHC molecules are eliminated?

<p>Negative selection (C)</p> Signup and view all the answers

What is the primary function of CD8 T-cells?

<p>Killing infected cells (B)</p> Signup and view all the answers

What is the term for immature T-cells that express both CD4 and CD8?

<p>Double-positive T-cells (C)</p> Signup and view all the answers

What is the result of pre-TCR signaling in the development of cells expressing α and β as their TCR?

<p>Further rearrangement of TCR β genes stops (B)</p> Signup and view all the answers

What is the main function of positive selection in thymic selection?

<p>Recognition of self-MHC and self-peptide (B)</p> Signup and view all the answers

What is the composition of the pre-T cell receptor (pre-TCR)?

<p>β chain and pre-Tα (B)</p> Signup and view all the answers

What is the outcome of double positive cells that do not interact with MHC class I and II molecules?

<p>They undergo apoptosis (A)</p> Signup and view all the answers

What is the percentage of thymocytes that are double positive cells?

<p>Over 80% (B)</p> Signup and view all the answers

What is the role of thymic non-lymphoid cells in thymic selection?

<p>Expressing MHC molecule plus peptide (D)</p> Signup and view all the answers

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