Exam 2: Set 4 Flashcards
Immunological memory is important for an effective vaccine. Which one of the following sentences describes the underlying mechanisms for this most accurately?
A. Macrophages and B cells have developed optimal effector mechanisms towards the antigen contained in the vaccine and can during an infection with this antigen respond faster and more effectively
B. T -and B-cells have developed effector mechanisms towards the antigen contained in the vaccine and can during an infection with this antigen respond fast and effectively to prevent disease
C. T -and B-cells have developed effector mechanisms towards a certain virus or bacteria and can prevent us from infection
D. NK cells, T -and B-cells have developed effector mechanisms towards the antigen contained in the vaccine and can during an infection with this antigen respond faster and more effectively
B. T -and B-cells have developed effector mechanisms towards the antigen contained in the vaccine and can during an infection with this antigen respond fast and effectively to prevent disease
Apoptosis is physiological cell death genetically encoded and regulated. The main pathways of extrinsic apoptosis (mediated by cytotoxic cells) are receptor-mediated and granule exocytosis- mediated apoptosis. How are these different?
A. NK cells use granule mediated, whereas cytotoxic T cells use receptor mediated
B. Receptor mediated apoptosis requires susceptibility by the target cell, whereas any cell is a target of granule mediated apoptosis
C. Receptor mediated apoptosis is used against cancer cells, whereas virus infected cells are killed by granule mediated apoptosis
D. Receptor mediated apoptosis is the primary mechanism, whereas granule-mediated is the secondary mechanism based on preformed antibodies.
B. Receptor mediated apoptosis requires susceptibility by the target cell, whereas any cell is a
target of granule mediated apoptosis
Ag cross-presentation, the process in which exogenous antigens are presented on MHC class I molecules, is crucial for the generation of effector CD8+ T cell responses. Although multiple cell types are being described to be able to cross-present Ags, in vivo this task is mainly carried out by certain subsets of DCs. What is the sequence of events?
A. Antigen/microbe/cell is phagocytosed, degraded in lysosomes, loaded onto MHC class II and transported to the surface B. Antigen is translated to protein from phagocytosed microbial mRNA in the cystosol, transported into ER, loaded onto MHC class I and transported to the surface. C. Antigen/microbe/cell is phagocytosed and broken down in lysosomes, antigens are transported to cytosol for proteosomal degradation, transported to ER, loaded onto MHC class I and transported to the surface D. Antigen/microbe/cell is phagocytosed, transported to ER, degraded by proteasomes, loaded onto MHC class I, and transported to the surface E. Antigen/microbe/cell is phagocytosed, degraded in lysosomes, loaded onto MHC class I and transported to the surface
C. Antigen/microbe/cell is phagocytosed and broken down in lysosomes, antigens are transported to cytosol for proteosomal degradation, transported to ER, loaded onto MHC class I and transported to the surface
Immune responses in the adaptive immune system have to be turned on, and off again when the adequate reaction is fulfilled. Which statement below is correct?
A. CTLA-4 is expressed on activated B-cells
B. CTLA-4 gives a negative signals to B-cells
C. CTLA-4 on T-cells competes with CD28 for binding to B7 on B-cells
D. CTLA-4 gives an activation signal to T helper cells
C. CTLA-4 on T-cells competes with CD28 for binding to B7 on B-cells
The IL-2 receptor occurs in three forms that exhibit different affinities for IL-2. These include the low affinity monomeric IL-2Rα and the high-affinity trimeric IL-2Rαβy. Which cells typically express the high-affinity trimeric IL-2Rαβy?
A. Resting CD4+ T cells and Ag-activated CD8+ T cells
B. Ag-activated B cells and Ag-activated CD4+ T cells
C. Ag-activated CD4+ and Ag-activated CD8+ T cells
D. Naïve B cells and Ag-activated CD4+ T cells
E. Resting CD8+ T cells and Ag-activated CD4+ T cells
C. Ag-activated CD4+ and Ag-activated CD8+ T cells
Eosinophilia in allergic diseases such as allergic rhinitis or asthma is driven by allergen activated Th2 cells. Which cytokine is the most critical cytokine mediating increased eosinophils differentiation, activation and survival?
A. IL-4 B. IL-13 C. IFN-gamma D. IL-5 E. Eotaxin
D. IL-5
Once antigen has been detected by an innate immune cell, this information is communicated to T and B cells of the adaptive immune system. Thus, the innate immune system provides signals for the activation of the adaptive immune system. It does so by providing signals related to the context and molecular nature of antigenic epitopes. The adaptive immune system induces T cells to change from a naive phenotype to either an effector functional type or a memory phenotype. The Th1/Th2 phenotype reflects the outcome of naive T cell activation. In addition to the well-established Th1 and Th2 subsets recently so-called Th17 cells were described. Which cytokines are being released in high amounts by these subsets?
A. Th1: IFN-a, Th2: IL-15, Th17: IL-17 B. Th1: IL-1, Th2: IL-2, Th17: IL-17 C. Th1: IFN-y, Th2: IL-4, Th17: IL-22 D. Th1: IL-12, Th2: IL-4, Th17: IL-17 E. Th1: TNF-B, Th2: IL-6, Th17: IL-22
C. Th1: IFN-y, Th2: IL-4, Th17: IL-22
T-cell differentiation in the thymus generates a peripheral repertoire of mature T cells that mounts strong responses to foreign antigens but is largely unresponsive to self-antigens. This state of specific immunological tolerance to self-components involves both central and peripheral mechanisms. What is the fate of the T cells that have a high affinity for self-MHC?
A. Clonal expansion and migration to the peripheral lymph nodes
B. Clonal anergy
C. Migration to the peripheral lymphoid organs where they go into apoptosis
D. Deletion in the thymus via induction of apoptosis
E. Homing to the bone marrow as part of a feedback loop
D. Deletion in the thymus via induction of apoptosis
VDJ recombination is the process by which T cells and B cells randomly assemble different gene segments – known as variable (V), diversity (D) and joining (J) genes – in order to generate unique receptors (known as antigen receptors) that can collectively recognize many different types of molecule. If you had 50 V, 20 D, and 6 J regions able to code for a heavy chain and 40 V and 5 J-region genes able to code for a light chain, you could have a maximum repertoire of:
A. 76 +45 = 121 antibody specificities
B. 76 x 45 = 3420 specificities
C. (40 x 5) + (50 x 20 x 6) = 6200 specificities
D. (40 x 5) x (50 x 20 x 6) = 1,200,000 specificities
E. more than 1,200,000 specificities
E. more than 1,200,000 specificities
The intestinal mucosa harbors the largest population of IgA-secreting plasma cells (PC) in the human body, producing daily several grams of IgA. IgA has many functions, serving as a first-line barrier that protects the mucosal epithelium from pathogens, toxins and food antigens (Ag), shaping the intestinal microbiota, and regulating host-commensal homeostasis. Signals induced by commensal colonization are central for regulating IgA induction, maintenance, positioning and function and the number of IgA-producing PC is dramatically reduced in neonates and germ- free (GF) animals. If you could analyze at the molecular level a plasma cell making lgA antibody, you would find all of the following except :
A. DNA sequence for V, D, and J genes translocated near the C alpha DNA exon
B. mRNA specific for either kappa or lambda light chains
C. mRNA specific for J chains
D. mRNA specific for u chains
E. DNA sequence coding for the T-cell receptor for antigen
D. mRNA specific for u chains
Signaling through the BCR is required for peripheral B lymphocyte maturation, maintenance, activation and silencing. In mature B cells, the antigen receptor normally consists of two isotypes, membrane IgM and IgD (mIgM, mIgD). Although the signals initiated from both isotypes differ in kinetics and intensity, the BCR of either isotype seems to be able to compensate for the loss of the other. The ability of a single B cell to express both lgM and IgD molecules on its surface at the same time is made possible by:
A. allelic exclusion
B. isotype switching
C. simultaneous recognition of two distinct antigens
D. alternative RNA splicing
E. use of genes from both parental chromosomes
D. alternative RNA splicing
Genes capable of encoding a complete antibody heavy or light chain do not exist as such within the DNA of most cells. The complete genes are assembled by the union of separate gene segments. Within B cells, these genes rearrange their relative positions to create a “mature” immunoglobulin gene that can encode a functional protein. This rearrangement process is the core of the immune system’s ability to generate antibodies capable of recognizing the tremendous variety of antigenic structures in nature. Which of the following statements concerning the organization of lg genes is correct?
A. V and J regions of embryonic DNA have already undergone a rearrangement.
B. Light-chain genes undergo further rearrangement after surface IgM is expressed.
C. VH gene segments can rearrange with Jkappa or Jlambda gene segments.
D. The VDJ segments coding for an Ig VH region may associate with different heavy-chain constant-region genes.
E. After VDJ joining has occurred, a further rearrangement is required to bring the VDJ unit
next to the Cu gene.
D. The VDJ segments coding for an Ig VH region may associate with different heavy-chain constant-region genes.
Which of the following statements regarding a B cell expressing both lgM and lgD on its membrane is incorrect?
A. The light chains of the IgM and IgD have identical amino acid sequences.
B. The constant parts of the heavy chains of the IgM and IgD have different amino acid sequences.
C. The lgM and IgD have different antigenic specificities.
D. If it is triggered by antigen and T-cell signals to proliferate and differentiate, it may differentiate into a plasma cell that may secrete IgG, IgE, or IgA antibodies.
C. The lgM and IgD have different antigenic specificities.
Which of the following plays a role in changing the antigen binding site of a B cell after antigenic stimulation?
A. junctional diversity B. combinatorial diversity C. germline diversity D. somatic hypermutation E. differential splicing of primary RNA transcripts
D. somatic hypermutation
The generation of mature B lymphocytes bearing a BCR is controlled by an ordered developmental program initiated in the fetal liver or bone marrow. The final stages of development should be completed in peripheral lymphoid organs such as the spleen. Which of the following is expressed on the surface of the mature B lymphocyte?
A. CD40
B. MHC class II molecules C. CD19
D. IgM and Ig D
E. all of the above
E. all of the above
