True or False: Negative selection of transitional B cells in the spleen removes B cell clones whose BCR recognizes self antigens that weren't expressed in the bone marrow. 2. Which of the following statements about the pre-BCR is false? a. Signals in an antigen-independent manner. b. Consists of a rearranged immunoglobulin heavy chain paired with a surrogate light chain (VpreB + lambda5). c. Consists of a rearranged immunoglobulin light chain with a surrogate immunoglobulin heavy chain (VpreB). d. Transiently expressed with the IgM isotype in its constant region. 3. True or False: The class switch recombination of IgA antibodies is induced by TGF-beta or IL-21, and IgA antibodies can be transported across the placental interface as pentameric (5 member) oligomers. 4. A newborn infant has not started breastfeeding yet. Which isotype of maternal antibody/antibodies does the newborn have that they received from their mother while in utero? a. IgG only b. IgD only c. IgG and IgA d. IgE only e. IgA only 5. Which of the following statements about the enzyme activation-induced cytidine deaminase (AID) is true? a. Required for both somatic hypermutation and class-switch recombination in germinal center B cells b. All of these statements are true. c. Attacks single-stranded DNA to convert cytidine into uridine d. Can trigger both DNA mismatch repair and DNA base-excision repair pathways
Added by Michael W.
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True. Negative selection in the spleen removes B cell clones that recognize self antigens that were not expressed in the bone marrow. Show more…
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1. Immune cells remain in tissues and do not circulate in the blood. True / False 2. The ability of immune cells to disseminate throughout the body means that an immune response may be initiated at one site, but may be active at a distant location. True / False 3. Leukocyte recruitment to sites of infection or injury is a major part of the process of inflammation. 4. Leukocyte homing refers to the delivery of myeloid cells from the bone marrow to the lymph nodes, where they mature. 5. After their arrival in peripheral lymphoid tissues, lymphocytes perform the following roles, with the exception of one. Which one is it? a) Differentiate into effector lymphocytes b) Recognize antigen c) Return to the bone marrow where they instruct the formation of identical, antigen-specific lymphocytes d) Proliferate 6. Naive lymphocytes permanently reside in a lymph node until they are activated by an antigen-presenting cell. True / False 7. Prior to their adhesion to endothelial cells, leukocytes secrete chemokines. True / False 8. Which of the following accurately describes the effect of cytokines (secreted by sentinel cells) on endothelial cells? a) Decrease in the expression of adhesion molecules b) Increase in the adhesiveness of the endothelial cells for circulating myeloid cells c) Increase in the secretion of chemokine receptors d) Increase in the adhesiveness of the endothelial cells for circulating naive lymphocytes 9. Selectins promote high-affinity adhesion to endothelial cells. True / False 10. These selectins are found on the surface of endothelial cells. a) L selectins b) P selectins c) E selectins d) None of these selectins are found on endothelial cells
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Which of the following statements about the double negative (DN) population of developing thymocytes are true? a. All of these statements are true. b. Located in the cortex of the thymus. c. Subjected to beta selection as the first checkpoint in thymocyte maturation. d. Express the surrogate alpha chain (pTalpha) which pairs with a TCRbeta chain to form the preTCR. e. Turned on expression of RAG1/2 to form a rearranged TCRbeta chain via V/D/J recombination. 2. True or False: Cytotoxic CD8+ T cells can only kill one target cell once activated, since the release of cytotoxic molecules contained in their granules can also induce apoptosis in the T cell itself, as well as in surrounding healthy cells. a. True b. False 3. An important source of combinatorial diversity in lymphocyte antigen receptors is the splicing together of various V, D, and J gene segments. Which of these enzymes plays a key role in mediating combinatorial diversity during these rearrangements? a. RAG1/2 b. Lck c. Granzyme B d. PKC-theta
Adi S.
QUESTION 40 The process of T cell-dependent antibody responses follows sequential steps with the last event entailing the formation of an organized structure known as the germinal center. QUESTION 41 In order for T lymphocytes to undertake effector functions, they must interact with phagocytes, antigen-presenting cells (APCs), and B cells to recognize unprocessed antigen. QUESTION 42 Memory B Cells do not secrete antibodies, but they circulate in the blood and reside in mucosal and other tissues. QUESTION 43 Protein antigens stimulate the generation of short-lived plasma cells. Polysaccharides, nucleic acid, and lipid antigens are involved in isotype switching and affinity maturation. QUESTION 44 Conjugate vaccines are primarily composed of a hapten and carrier protein on the basis that humoral immunity will recognize negligible epitopes present but will orchestrate the activation of helper T lymphocytes because of the presence of carrier molecules.
Madhur L.
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