Exam 4 Review
Signaling through the pre-TCR results in: maturation to the DN4 stage suppression of TCR β-chain rearrangement cessation of proliferation TCR α-chain rearrangement All of the above
All of the above Hint: Development does not progress until there is a signal through the pre-TCR.
What happens to autoreactive cells that escape the thymus? They attack self tissues They can be rendered anergic They negatively regulate other autoreactive cells They require TCR-ligation and costimulation to be activated All of the above
All of the above Hint: Not all self antigens are expressed in the thymus.
Superantigens differ from regular peptide antigens because they: bind outside the peptide-binding groove activate a larger proportion of T cells interact with the Vβ domain of the TCR can result in toxic shock All of the above
All of the above Hint: Superantigens produced by some bacteria cause polyclonal activation of T cells.
Which of the following statements concerning CTL-medicated lysis is not true? Is antigen specific Requires cell contact CTLs are not injured Involves apoptosis All of the above statements concerning CTL lysis are true
All of the above statements concerning CTL lysis are true
Explain why T cells are more likely to develop into αβ T cells than γδ T cells.
Answer: Because, once a cell successfully produces a β chain, the preTCR is expressed. In order for a cell to become γδ, it must successfully rearrange γ and δ before β, and the chances of that are much smaller. Section: Early Thymocyte Development Difficulty: 3 Hint: It has to do with somatic recombination.
The cellular basis of clonal deletion in the thymus is programmed cell death called: Necrosis Perforin polymerization Apoptosis Cell suicide None of the above
Apoptosis
The costimulatory signal that guarantees that only professional APCs can initiate a T cell response is the: Binding of APC's B7 to T cell's CD28 Binding of T cell's B7 to APC's CD28 Binding of APC's peptide antigen to T cell's CD3 Binding of APC's peptide antigen to B cell's surface IgE Binding of CD3 to TCR
Binding of APC's B7 to T cell's CD28
Committed lymphocyte progenitors originate in the: Thymus Bone marrow Spleen Lymph node Brain
Bone marrow
Current research suggests that members in one subpopulation of helper T cells may be able to change the cytokines they produce to mimic or become members of another subpopulation of helper T cells. What advantage(s) would the ability to change helper T cell subpopulations have in an immune response? A more rapid and specific response to an immune threat Ability of the immune system to recover function during an autoimmune disease The continued expression of a particular subset of TH cells after that subset has been cross-regulated Both A and B Both B and C
Both A and B
Which type of professional antigen-presenting cells is a naïve T cell most likely to encounter? B cell Dendritic cell Macrophage Both A and B Both B and C
Both A and B
Which of the following is required for T-cell activation? Antigen-specific TCR binding to MHC molecule Expression of CD4 or CD8 Interaction with CD80/CD86 Both A. and B Both A. and C
Both A. and C
TSST-1 is a protein produced by some species of bacteria that acts as a superantigen. What ligand does TSST-1 bind? T-cell receptor MHC class I MHC class II Both T-cell receptor and MHC class I Both T-cell receptor and MHC class II
Both T-cell receptor and MHC class II
The MHC restriction of T helper cells involves: CD4 and class I MHC CD4 and class II MHC CD4 and class III MHC CD8 and class I MHC CD8 and class II MHC
CD4 and class II MHC
What is currently the best explanation for what determines whether a T cell develops into a CD8+ T cell or a CD4+ T cell? CD4/TCR coengagement suppresses CD8 expression, and CD8/TCR coengagement suppresses CD4 expression T cells randomly down-regulate CD4 or CD8, and only cells that still bind the appropriate MHC will get a strong enough signal to survive CD4 or CD8 expression is determined by the strength and duration of the TCR/MHC interaction CD4 or CD8 expression is predestined in the bone marrow Only γδ T cells express CD8.
CD4 or CD8 expression is determined by the strength and duration of the TCR/MHC interaction. Hint: The kinetic model has the greatest experimental support.
The MHC restriction of T cytotoxic cells involves: CD4 and class I MHC CD4 and class II MHC CD4 and class III MHC CD8 and class I MHC CD8 and class II MHC
CD8 and class I MHC
The T cell that exits the thymus and will develop into a cytotoxic T cell is the: CD4+ T cell CD8+ T cell CD4+,8+ T cell CD4-,8-, gamma-delta TCR+ T cell None of the above T cell
CD8+ T cell
CTLA-4 is a co-stimulatory receptor on T cells that belongs to the same family as the CD28 co-stimulatory receptor. However, CTLA-4 is antagonistic to CD28. Which of the following could be a functional advantage of CTLA-4 expression within the immune response? CTLA-4 competes with CD28 for ligand binding so that, if CD28 binds to its ligand, the response will be magnified. CTLA-4 is often given to immunosuppressed individuals to trigger an immune response. CTLA-4 limits the immune response of TC and TH cells after an infection has been cleared. CTLA-4 limits TC activity in healthy individuals during a viral infection. CTLA-4 reduces the lag time between antigen presentation to a TH cell and B cell activation.
CTLA-4 limits the immune response of TC and TH cells after an infection has been cleared.
At what stage of T cell development is the pre-TCR expressed? DN DP SP Pro-T cell None of the above
DN
Which of the following represents the earliest stage in T-cell development? Single positive-CD4 Single positive-CD8 Double positive Double negative Mature T cell
Double negative
Which of the following is MOST likely to simulate a memory T cell? B cell Dendritic cell Memory cell Either A or B Either A, B, or C
Either A, B, or C
Which transcription factor is characteristic of TREG cells? AP-1 NFAT NFκB OCT-1 FOXP3
FOXP3
Ligation of which of the following cell-surface receptors leads to cell death? TCR TLR Fas Caspase-8 Bcl-2
Fas Hint: Note that the question asks about cell-surface receptors.
In carrying out its helper function, T helper cells respond to APC and: Foreign peptide fragment alone Foreign peptide fragment in context with class I MHC protein Foreign peptide fragment in context with class II MHC protein Foreign peptide fragment in context with class III MHC protein T helper cells only respond to American made peptide fragments
Foreign peptide fragment in context with class II MHC protein
TH17 effector cytokines are: IFN-gamma, TNF IL-4, IL-5, IL-13 IL-17, IL-22 IL-10, TGF-beta IL-4, IL-21
IL-17, IL-22
T-cell activation requires antigen being displayed in the context of an APC and interaction between co-stimulatory molecules on the APC and the T cell. In addition to these two signals, T-cell activity is often influenced by cytokines. Which of the following is an example of how cytokines can influence T-cell activity in the presence of MHC presentation and co-stimulatory ligand interaction? CD28 causes memory NK cells to be produced. CD8 triggers apoptosis in T cells that recognize self-antigens. IL-2 triggers T-cell proliferation. Opsonins recruit eosinophils to present carbohydrate antibodies to naïve TC cells. TNF-α increases the production of IgM by activated T cells.
IL-2 triggers T-cell proliferation.
TREG polarizing cytokines are: INF-gamma, IL-12, IL-18 IL-4 IL-6, TGF-beta. IL-2, TGF-beta IL-6, IL-21
IL-2, TGF-beta
TH1 polarizing cytokines are: INF-gamma, IL-12, IL-18 IL-4 IL-6, TGF-beta. IL-2, TGF-beta IL-6, IL-21
INF-gamma, IL-12, IL-18
Mycobacterium leprae, the causative agent of leprosy in humans, is an intracellular pathogen that resides in the phagosome of macrophages. Leprosy presents in two main clinical manifestations. Tuberculoid leprosy results in the formation of granulomas and a cell-mediated immune response while lepromatous leprosy results in the production of high levels of IgG (hypergammaglobulinemia). If TH2 is produced in high levels during an M. leprae infection, which type of leprosy would result? Lepromatous leprosy Tuberculoid leprosy Either lepromatous leprosy or tuberculoid leprosy Neither one; leprosy depends on the expression of TREG cells Cannot determine; insufficient clinical evidence to support either outcome
Lepromatous leprosy
T cells are frequently at fault for causing damage in autoimmune disorders and in transplant rejection. As an immunologist, your dream is to discover a method for decreasing T-cell response to self-antigens. Which of the following would be the BEST target for your research? Activated B cells because they make T cell receptor molecules Antibody-mediated apoptosis of dendritic cells CTLA-4 antagonists that block the action of CTLA-4 Ligands that block the binding of one co-stimulatory molecule Radiation therapy directed at all T cells
Ligands that block the binding of one co-stimulatory molecule
CD4+ T cells recognize: CD8+ molecules IgM MHC class I peptides MHC class II peptides MHC class III peptides
MHC class II peptides
For pathogenic peptides to be seen as foreign, they must be bound by a T cell in the context of a/an: B-7 molecule CD molecule IgM molecule MHC molecule Pattern recognition receptor molecule
MHC molecule
Which of the following are characteristics of apoptosis? Membrane blebbing Swelling of the cytoplasm Increased metabolism Release of cellular contents into the extracellular space All of the above
Membrane blebbing Hint: Apoptosis occurs naturally and does not necessarily lead to inflammation.
Memory T cells, effector T cells, and naïve T cells share several characteristics. Which of the following descriptions could only be said of memory T cells? Memory T cells are activated by any APC Memory T cells are only found in one location and do not circulate Memory T cells express CD44, CD62L, and CCR7 Memory T cells recognize MHC class I or class II peptides displaying antigen molecules Memory T cells depend upon co-stimulatory signals from CD2/ LFA-3, CD45R/ CD22, and LFA-1/ ICAM-2.
Memory T cells are activated by any APC
Which type of lymphocyte provides a very early response to viral infections? Memory T NK TC TH1 TH2
NK
Injecting a TCR transgenic mouse with the peptide that it recognizes would result in an increase in which process? Positive selection Negative selection Complement fixation Phagocytosis All of the above
Negative Selection Hint: T cells that receive strong signals during development die.
Hematopoietic stem cells cultured in the presence of which receptor differentiate into T cells rather than B cells. CD4 CD8 Notch B-7 CD3
Notch
Which type of T cell helps B cell development in the germinal centers? TH1 TH2 TH17 TREG TFH.
TFH.
Which type of T cell regulates allergic reactions and protects against extracellular pathogens? TH1 TH2 TH17 TREG TFH.
TH2
Which type of lymphocyte directs and regulates B-cell activity and differentiation? Memory T NK TC TH1 TH2
TH2
Which type of T cell inhibits inflammation? TH1 TH2 TH17 TREG TFH.
TREG
What event initiates an adaptive immune response? The interaction of a mature B cell with a mature TH cell. The expression of cytokines CD4 or CD8. The production of MHC class I or class II molecules. The interaction of a naïve T cell with a professional APC. The phagocytosis of a pathogen by a macrophage.
The interaction of a naïve T cell with a professional APC.
Naïve CD4+ and CD8+ T cells leave the __________ and enter the circulation. Bone marrow Liver Lymph node Spleen Thymus
Thymus
Follicular helper T cells are a recent discovery in the Helper T-cell lineage. What is the primary role of TFH cells? To help B cell development in germinal centers To regulate TREG cell activity To stimulate dendritic cell production To suppress B-cell activation after pathogen has been cleared To suppress TC cells after an infection has been cleared
To help B cell development in germinal centers
What is the function of a memory T cell? To activate TC and TH cells during an active primary infection To avoid autoimmune disorders by producing memory for self-antigens during T-cell development To maintain an active T-cell response (TC or TH) after an infection is cleared To provide an almost immediate response upon subsequent exposure to a specific pathogen To suppress TC activity after a pathogen is cleared
To provide an almost immediate response upon subsequent exposure to a specific pathogen
PD-1 is a negative co-stimulatory signal expressed by tumor cells. What advantage would the expression of PD-1 have in a tumor cell avoiding the immune response? None. Tumor cells are recognized as self and therefore do not pose a health threat. Tumor cells can avoid being killed by activated TC cells. Tumor cells can avoid apoptosis triggered by TH cells. Tumor cells avoid phagocytosis by dendritic cells. Tumor cells are stimulated to reproduce much faster than tumor cells that do not express PD-1.
Tumor cells can avoid being killed by activated TC cells.
During immune surveillance, T cytotoxic cells respond to: Viral peptide antigens alone Viral peptide antigens in context with class I MHC proteins Viral peptide antigens in context with class II MHC proteins Viral peptide antigens in context with class III MHC proteins T cytotoxic cells do not respond to viral peptide antigens
Viral peptide antigens in context with class I MHC proteins
In negative selection, thymocytes that receive ________ signal through their TCRs die. a weak a strong an intermediate no an intermittent
a strong
Cross-regulation of various members of a subset of T cells is frequently observed with: all TC cells all TH cells only TC 1 subset only T1 subset only TREG subset.
all TH cells
Committed lymphocyte progenitors originate in the: thymus bone marrow spleen lymph node brain.
bone marrow
ith respect to T-cell activation, effector molecules trigger all of the following functions EXCEPT: cell-cycle entry cell division to produce additional T cells. cell differentiation into various types of T cells cell stimulation of B cells cell survival.
cell stimulation of B cells
All of the following are functions of TH1 cells EXCEPT: contributes to autoimmunity enhances APC activity enhances TC activity involved with delayed type hypersensitivity reactions protects against intracellular pathogens.
contributes to autoimmunity
TH17 cells are involved with all of the following EXCEPT: autoimmunity delayed-type hypersensitivity inflammatory response protection against fungal infections protection against bacterial infections.
delayed-type hypersensitivity
A naïve T cell refers to a T cell that: does not express CD4+ or CD8+ has not left the bone marrow has not yet encountered an antigen is not mature resides in the thymus.
has not yet encountered an antigen
Signaling through the pre-TCR occurs as a result of: binding to MHC class I binding to MHC class II binding to either MHC class I or MHC class II successful assembly of the pre-TCR expression of CD4
successful assembly of the pre-TCR