Chapter 7 Flashcards
In which of the following ways does the developmental pathway of α:β T cells differ from that of B cells? (Select all that apply.)
a. Their antigen receptors are derived from gene rearrangement processes.
b. When the first chain of the antigen receptor is produced it combines with a surrogate chain.
c. Cells bearing self-reactive antigen receptors undergo apoptosis.
d. MHC molecules are required to facilitate progression through the developmental pathway.
e. T cells do not rearrange their antigen-receptor genes in the bone marrow.
d. MHC molecules are required to facilitate progression through the developmental pathway.
e. T cells do not rearrange their antigen-receptor genes in the bone marrow.
Which of the following cell-surface glycoproteins is characteristic of stem cells, but stops being expressed when a cell has committed to the T-cell developmental pathway?
a. CD2
b. CD3
c. CD25
d. CD34
e. MHC class II
CD34
Which of the following processes is not dependent on an interaction involving MHC class I or class II molecules? (Select all that apply.)
a. positive selection of α:β T cells
b. intracellular signaling by pre-T-cell receptors
c. negative selection of αβ T cells
d. peripheral activation of mature naive T cells
e. positive selection of γ:δ T cells
b. intracellular signaling by pre-T-cell receptors
e. positive selection of γ:δ T cells
If a double-negative thymocyte has just completed a productive β-chain gene rearrangement, which of the following describes the immediate next step in the development of this thymocyte?
a. A pre-T-cell receptor is assembled as a superdimer.
b. Rearrangement of γ- and δ-chain genes commences.
c. Expression levels of RAG-1 and RAG-2 are elevated.
d. The linked δ-chain genes are eliminated.
e. This cell will inevitably differentiate into a committed γ:δ T cell.
A pre-T-cell receptor is assembled as a superdimer.
All of the following cell-surface glycoproteins are expressed by double-negative thymocytes undergoing maturation in the thymus except _____. (Select all that apply.)
a. CD2
b. CD5
c. CD127 (IL-7 receptor)
d. CD34
e. CD1A
f. CD4
d. CD34
f. CD4
_____ is a T-cell-specific adhesion molecule expressed before the expression of a functional T-cell receptor while the thymocytes are still in their double-negative stage of development.
a. CD4
b. CD8
c. CD25
d. CD2
e. CD3
CD2
Which of the following is mismatched:
a. double-negative CD3– thymocytes: cortico-medullary junction
b. double-negative CD3– thymocytes: subcapsular zone
c. double-positive CD3+ thymocytes: cortico-medullary junction
d. cortical epithelial cells: subcapsular regions
e. dendritic cells: cortico-medullary junction
double-negative CD3– thymocytes: cortico-medullary junction
After interaction with thymic stromal cells, _____, a glycoprotein not expressed by the uncommitted progenitor cell is activated in developing thymocytes. (Select all that apply.)
a. CD2
b. CD34
c. CD5
d. CD127 (IL-7 receptor)
e. CD44
a. CD2
c. CD5
d. CD127 (IL-7 receptor)
Which of the following statements about Notch 1 is correct? (Select all that apply.)
a. Notch 1 is expressed on thymic epithelial cells.
b. In the absence of Notch 1 expression, T cells can complete their differentiation.
c. Notch 1 is to T-cell development as Pax-5 is to B-cell development.
d. Notch 1 contains two distinct domains, one of which is proteolytically cleaved and becomes a transcription factor in the nucleus.
e. The extracellular domain of Notch 1 must interact with a ligand on thymic epithelium to initiate cleavage and separation of the Notch 1 extracellular and intracellular domains.
c. Notch 1 is to T-cell development as Pax-5 is to B-cell development.
d. Notch 1 contains two distinct domains, one of which is proteolytically cleaved and becomes a transcription factor in the nucleus.
e. The extracellular domain of Notch 1 must interact with a ligand on thymic epithelium to initiate cleavage and separation of the Notch 1 extracellular and intracellular domains.
Which of the following is the first stage of T-cell receptor gene rearrangement in α:β T cells?
a. Vα→Dα
b. Dα →Jα
c. Vβ→ Dβ
d. Dβ→Jβ
e. Vα→Jα
Dβ→Jβ
Which of the following is the first T-cell receptor complex containing the β chain to reach the cell surface during the development of T lymphocytes?
a. γ:β:CD3
b. β:CD3
c. α:β:CD3
d. β:CD44
e. pTα:β:CD3
pTα:β:CD3
Genetic deficiencies in all of the following would impair the development of a fully functional T-cell repertoire except
a. RAG-1 or RAG-2
b. Notch1
c. Pax-5
d. IL-7 receptor (CD127)
e. TAP-1 or TAP-2
Pax-5
There are many parallels between the development of B cells and T cells. Identify the incorrectly matched counterpart in B cells (left) versus T cells (right).
a. VpreBλ5: pTα
b. Igα/Igβ:CD3
c. Pax-5: FoxP3
d. multiple κ and λ light-chain gene rearrangements: multiple α-chain gene rearrangements
Pax-5: FoxP3
Which of the following statements are true of a T cell that expresses two α chains (and thus two different T-cell receptors) as a result of ineffective allelic exclusion of the α chain during rearrangement? (Select all that apply.)
a. Engaging either of the T-cell receptors on MHC molecules of the thymic epithelium will result in positive selection.
b. One of the T-cell receptors will be functional while the other will most probably be non-functional.
c. If either T-cell receptor binds strongly to self-peptides presented by self-MHC molecules, the thymocyte will be negatively selected.
d. One of the T-cell receptors may be autoreactive but escape negative selection because its peptide antigen is present in tissues other than the thymus.
e. Subsequent gene rearrangements may give rise to a γ:δ T-cell receptor.
a. Engaging either of the T-cell receptors on MHC molecules of the thymic epithelium will result in positive selection.
b. One of the T-cell receptors will be functional while the other will most probably be non-functional.
c. If either T-cell receptor binds strongly to self-peptides presented by self-MHC molecules, the thymocyte will be negatively selected.
d. One of the T-cell receptors may be autoreactive but escape negative selection because its peptide antigen is present in tissues other than the thymus.
Once a thymocyte has productively rearranged a β-chain gene, which of these event(s) can occur subsequently? (Select all that apply.)
a. β binds to pTα and is expressed on the cell surface with the CD3 complex and ζ chain.
b. Rearrangement of β-, γ-, and δ-chain genes ceases as a result of the suppression of expression of RAG-1 and RAG-2.
c. The pre-T cell proliferates and produces a clone of cells all expressing an identical β chain.
d. Expression of CD34 and CD2 gives rise to double-positive thymocytes.
e. α-, γ-, and δ-chain loci rearrange simultaneously.
a. β binds to pTα and is expressed on the cell surface with the CD3 complex and ζ chain.
b. Rearrangement of β-, γ-, and δ-chain genes ceases as a result of the suppression of expression of RAG-1 and RAG-2.
c. The pre-T cell proliferates and produces a clone of cells all expressing an identical β chain.
e. α-, γ-, and δ-chain loci rearrange simultaneously.
Which of the following statements regarding positive selection is correct?
a. All subsets of developing T cells undergo positive selection before export to the peripheral circulation.
b. T-cell receptor editing is linked to the process of positive selection.
c. Positive selection results in the production of T cells bearing T-cell receptors that have the capacity to interact with all allotypes of MHC class I and class II molecules, and not just those of the individual.
d. Positive selection ensures that autoreactive T cells are rendered non-responsive.
e. If there is a genetic defect in AIRE, then T-cell development is arrested as positive selection commences.
T-cell receptor editing is linked to the process of positive selection.
Thymocytes that are not positively selected
a. undergo genetic reprogramming and differentiate into a different cell type
b. are exported to the periphery, where they are phagocytosed by macrophages
c. make up about 98% of developing thymocytes and die by apoptosis in the thymic cortex
d. are eliminated because of their reactivity with self antigens
e. try out different β chains to acquire reactivity with self-MHC molecules
make up about 98% of developing thymocytes and die by apoptosis in the thymic cortex
If the process of positive selection did not occur, then
a. a condition resembling immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX) would develop
b. a condition resembling autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED) would develop
c. naive T cells would be unable to undergo differentiation in secondary lymphoid tissues
d. malignant transformation would be more likely because of the accumulation of multiple mutations
e. only a very small percentage of circulating T lymphocytes would be able to become activated
only a very small percentage of circulating T lymphocytes would be able to become activated
Immediately after positive selection
a. the thymocyte reaches maturity and is exported to the periphery
b. RAG proteins are degraded and are no longer synthesized
c. receptor editing commences to eliminate reactivity against self antigens
d. the developing thymocyte acquires a double-negative phenotype
e. expression of pTα is repressed
RAG proteins are degraded and are no longer synthesized
Allelic exclusion occurs for all of the following except
a. T-cell receptor α genes
b. T-cell receptor β genes
c. B-cell receptor heavy-chain genes
d. B-cell receptor κ-chain genes
e. B-cell receptor λ-chain genes
T-cell receptor α genes
Autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED) is caused by a defect in
a. cathepsin L
b. a transcription factor that regulates tissue-specific gene expression in the thymus
c. the production of regulatory CD4 T cells
d. FoxP3
e. T-cell receptor gene rearrangement
a transcription factor that regulates tissue-specific gene expression in the thymus
Identify which of the following describes how antigen processing and presentation of self antigens by thymic epithelial cells differs from that of antigen-presenting cells in peripheral tissues. (Select all that apply.)
a. Thymic epithelium expresses MHC class I molecules but not MHC class II molecules.
b. Thymic epithelium uses cathepsin L for proteolytic degradation of self proteins.
c. Thymic epithelium expresses MHC class II molecules but not MHC class I molecules.
d. Thymic epithelium uses the transcription factor AIRE to activate thymic expression of tissue-specific genes.
e. Thymic epithelium expresses transcription repressor protein FoxP3.
b. Thymic epithelium uses cathepsin L for proteolytic degradation of self proteins.
d. Thymic epithelium uses the transcription factor AIRE to activate thymic expression of tissue-specific genes.
All of the following types of protein are processed and presented by macrophages in the thymus except _____ proteins.
a. tissue-specific
b. soluble proteins from extracellular fluids
c. ubiquitous proteins
d. proteins made by macrophages
e. proteins derived from other cells that macrophages phagocytose
tissue-specific
Healthy individuals have approximately ____ of CD4 T cells compared with CD8 T cells.
a. one quarter the number
b. half the number
c. equal numbers
d. twice the number
e. four times the number
twice the number
Double-negative thymocytes initiate rearrangement at the _____ locus (loci) before all other T-cell receptor genes.
a. γ and δ
b. β
c. α and β
d. α, γ, and δ
e. β, γ, and δ
β, γ, and δ
The function of negative selection of thymocytes in the thymus is to eliminate
a. single-positive thymocytes
b. double-positive thymocytes
c. alloreactive thymocytes
d. autoreactive thymocytes
e. apoptotic thymocytes
autoreactive thymocytes