Immunology FIT Board Review: Abbas 7th Ed

Immunology Review: Abbas 7th Ed Latest Question and Answer 2023/2024 Cytokines are not usually stored as preformed molecules, and their synthesis is initiated by new gene transcription as a result of cellular activation. Such transcriptional activation is transient, and the messenger RNAs encoding most cytokines are unstable and often rapidly degraded, so cytokine synthesis is also transient. Once synthesized, cytokines are rapidly secreted, resulting in a burst of release when needed... Cytokines share many other general properties. One cytokine can act on diverse cell types and have multiple biologic effects, a property that is referred to as pleiotropism... Most cytokines act close to where they are produced, either on the same cell that secretes the cytokine (autocrine action) or on a nearby cell (paracrine action). When produced in large amounts, cytokines may enter the circulation and act at a distance from the site of production (endocrine action). Tumor necrosis f - ANSWER One general property of cytokines is: A. They are stored as preformed molecules primed for rapid release. B. They are constitutively transcribed and released. C. They can act on many different kinds of cells. D. They have strictly local (autocrine or paracrine) biologic effects. C, page 11 Because the number of naive lymphocytes specific for any antigen is very small (on the order of 1 in 105 or 106 lymphocytes) and the quantity of the available antigen may also be small, special mechanisms are needed to capture microbes, to concentrate their antigens in the correct location, and to deliver the antigens to specific lymphocytes. - ANSWER The number of naive lymphocytes specific for a given antigen is on the order of A. 100 B. 10^2-10^3 C. 10^5-10^6 D. 10^8-10^9 D, page 11: See legend to figure 1-6 The response contracts (declines) as antigen-stimulated lymphocytes die by apoptosis, restoring homeostasis, and the antigen-specific cells that survive are responsible for memory. - ANSWER The main mechanism by which contraction of the immune response occurs is: A. Differentiation B. Clonal expansion C. Clonal selection D. Apoptosis B, page 12 One of the earliest responses of CD4+ helper T cells is secretion of the cytokine interleukin-2 (IL-2). IL-2 is a growth factor that acts on the antigen-activated lymphocytes and stimulates their proliferation (clonal expansion) ... Other CD4+ effector T cells secrete cytokines that stimulate the production of a special class of antibody called immunoglobulin E (IgE) and activate leukocytes called eosinophils, which are able to kill parasites that may be too large to be phagocytosed. - ANSWER One important effect of IL-2 is A. It serves as a growth factor for naive lymphocytes. B. It drives clonal expansion. C. It stimulates production of IgE antibodies. D. It prevents complement activation on host cells. A, page 2 Mechanisms for defending the host against microbes are present in some form in all multicellular organisms. These mechanisms constitute innate immunity. The more specialized defense mechanisms that constitute adaptive immunity are found in vertebrates only. - ANSWER A vaccine has been developed for elm trees that prevents infection with the fungus that causes Dutch elm disease. The vaccine contains a non-pathogenic fungus of a different species. What is the likely mechanism of action for this vaccine? A. Enhancement of innate immune mechanisms. B. Induction of an anti-fungal antibody response. C. Induction of a memory T cell response. D. Passive transfer of immunity. A, page 13 The response of B cells to protein antigens requires activating signals ("help") from CD4+ T cells (which is the historical reason for calling these T cells "helper" cells). B cells can respond to many non-protein antigens without the participation of other cells. - ANSWER In order to respond to protein antigen, additional help from what cell type is required? A. CD4+ T cells B. CD8+ T cells C. NK cells D. NKT cells C, pages 4-5 Immunity can be conferred on an individual by transferring serum or lymphocytes from a specifically immunized individual, a process known as adoptive transfer in experimental situations. The recipient of such a transfer becomes immune to the particular antigen without ever having been exposed to or having responded to that antigen. Therefore, this form of immunity is called passive immunity. Passive immunization is a useful method for conferring resistance rapidly, without having to wait for an active immune response to develop. Passive immunization against toxins by the administration of antibodies from immunized animals is a lifesaving treatment for potentially lethal infections, such as tetanus, and snake bites. - ANSWER A 42-year-old male arrives to the emergency room of his local hospital after having received a deep laceration to his hand while working in his backyard. The physician on duty decides to administer tetanus immune globulin as part of treatment. This is an example of which type of immunity? A. Innate immunity B. Active immunity C. Passive immunity D. Cell-mediated immunity B, page 13 Polysaccharides and lipids stimulate secretion mainly of the antibody class called IgM. Protein antigens induce the production of antibodies of functionally different classes (IgG, IgA, IgE). - ANSWER Polysaccharides and lipids stimulate secretion mainly of which antibody class? A. IgA B. IgM C. IgG D. IgE D, page 6 Immune responses are specific for distinct antigens and, in fact, for different portions of a single complex protein, polysaccharide, or other macromolecule (Fig. 1-4). The parts of such antigens that are specifically recognized by individual lymphocytes are called determinants or epitopes. - ANSWER Immune responses are specific even for different portions of a complex antigen. The parts of such complex antigens specifically recognized by individual lymphocytes are called what? A. Induction points B. Adjuvants C. Expanders D. Epitopes C, page 3, Table 1-2, Diversity in innate immunity is limited and is germline encoded. Somatic recombination increases the diversity of adaptive immunity. Both the innate and adaptive immune system have mechanisms to avoid self-reactivity. - ANSWER Which of the following is a distinguishing characteristic of the innate, as opposed to the adaptive, immune system? A. More diverse. B. non-reactive to self. C. Germline-encoded. D. Diversity produced by somatic recombination B, page 19 Basophils are derived from bone marrow progenitors (a lineage different from that of mast cells), mature in the bone marrow, and circulate in the blood. Although they are normally not present in tissues, basophils may be recruited to some inflammatory sites. Basophils contain granules that bind basic dyes. Like mast cells, basophils express IgG and IgE receptors. - ANSWER Which of the following statements about basophils is true? A. They are not normally found in the circulation but are constitutively present in healthy tissues. B. They are derived from a bone marrow lineage different from that of mast cells. C. Mature basophils express IgM and IgD receptors. D. Their granules contain basic proteins that bind acidic dyes. A, page 18 Macrophages can acquire distinct functional capabilities, depending on the types of activating stimuli. The clearest example of this is the response of macrophages to different cytokines made by subsets of T cells. Some of these cytokines activate macrophages to become efficient at killing microbes, called classical activation. Other cytokines activate macrophages to promote tissue remodeling and repair, called alternative activation. - ANSWER Alternative activation of macrophages promotes what function(s)? A. Tissue modeling and repair. B. Efficient ingestion and killing of microbes. C. Killing cells infected with viruses or intracellular bacteria. D. Secretion of enzymes that are toxic to the cell walls of parasites. A, page 26 The distinguishing features of naive, effector, and memory lymphocytes reflect different programs of gene expression that are regulated by transcription factors and by stable epigenetic changes. For example, a transcription factor called Kruppel-like factor 2 (KLF-2) is required for maintenance of the naive T cell phenotype. The phenotypes of functionally different types of CD4+ effector T cells, called TH1, TH2, and TH17 cells, depend on transcription factors T-bet, GATA-3, and RORγT, respectively, as well as epigenetic changes in cytokine gene loci. - ANSWER Which of the following transcription factors is required for maintenance of the naive T cell phenotype? A. Kruppel-like factor 2 (KLF-2) B. T-bet C. GATA3 D. RORγT D, page 32 Naive B cells express a chemokine receptor, CXCR5, that recognizes a chemokine, CXCL13, produced only in follicles by FDCs. Thus, B cells are attracted into the follicles, which are the B cell zones of lymph nodes. Another cytokine (which is not a chemokine) called lymphotoxin plays a role in stimulating CXCL13 production, especially in the follicles. CXCR5 knockout mice lack B cell-containing follicles in lymph nodes and spleen. - ANSWER Naïve B cells express CXCR5, which attracts them to what chemokine and cell type? A. CCL19 produced by stromal cells in the T cell zones of the lymph node. B. CXCL12 produced in the bone marrow. C. CXCL9 produced by endothelium at sites of chronic inflammation. D. CXCL13 produced by follicular dendritic cells. D, page 17, legend to figure 2-2 Both dendritic cells and monocytes arise from a common precursor cell of the myeloid lineage in the bone marrow, and differentiation into monocytes or dendritic cells is driven by the cytokines monocyte colony-stimulating factor and Flt3 ligand, respectively. - ANSWER Which cytokine promotes differentiation of the monocyte/dendritic cell precursor into the common dendritic cell precursor? A. G-CSF B. GM-CSF C. C-kit ligand D. Flt3 ligand A, page 34 and Figure 2-15 The architecture of the white pulp is analogous to the organization of lymph nodes, with segregated T cell and B cell zones. In the mouse spleen, the central arteries are surrounded by cuffs of lymphocytes, most of which are T cells. Because of their anatomic location, morphologists call these T cell zones periarteriolar lymphoid sheaths... The architecture of the white pulp is more complex in humans than mice, with both inner and outer marginal zones and a perifollicular zone. - ANSWER The T cell zones of the mouse spleen are primarily located in: A. Periarterioloar lymphatic sheath B. Marginal zones C. Lymphoid follicles D. Red pulp A, page 34 The B cells in the marginal zone, known as marginal zone B cells, are functionally distinct from follicular B cells and have a limited repertoire of antigen specificities. Both marginal zone and follicular B cells express CD21 and differentiate into plasma cells. Neither are predominantly located in the periarteriolar lymphatic sheath. - ANSWER One feature that distinguishes marginal zone B cells from follicular B cells is: A. They have a more limited repertoire of antigen specificities. B. They are predominantly located in the periarteriolar lymphatic sheath. C. They express CD21 on their surface. D. They do not differentiate into plasma cells. C, page 32