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A series of questions and verified answers related to mcmp 422, focusing on immunology, specifically b-cell and t-cell development. It covers topics such as hematopoietic stem cells, b-cell maturation stages, the role of various cell-surface markers (e.g., cd34), and the processes of receptor editing and negative selection in b-cells. Additionally, it addresses t-cell development, including thymocyte maturation, t-cell receptor rearrangements, and the involvement of mhc molecules. The questions are designed to test understanding of key concepts in immunology, making it a useful resource for students studying the immune system and its development.
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All hematopoietic stem cells express - Answer CD
Immature B cells develop into B cells in the - Answer secondary lymphoid organs.
Large pre-B cells are characterized by which of the following? - Answer μ is assembled with VpreBλ5.
The latest stages of late pro-B-cell development are recognized by the association of a surrogate light chain with a μ chain. The surrogate light chain is composed of - Answer VpreB and λ 5
Which of the following cell-surface markers identifies hematopoietic stem cells from among the other bone marrow cell constituents? - Answer CD
Which of the following best describes a large pre-B cell? - Answer VDJ has undergone successful rearrangement and μ heavy chain has been produced.
Which of the following is correct?
A key advantage of having two gene loci κ and λ, for the light chain is- Answers that the chance of a successful rearrangement of light-chain genes increases.
Large pre-B cells undergo clonal expansion prior to the rearrangement of light-chain loci. Of the options listed below which is NOT a favorable result of clonal expansion?
There are two major types of B cells designated as B-1 and B-2. Which of the following statements is true about B-1 cells? - Answer B-1 cells first appear in the fetus
When expression of _______ is turned off in small pre-B cells, the result is that about 50% of light-chain genes have P nucleotides but lack N nucleotides - Answer TdT
Choose all of those that are matched correctly. early pro-B cell: VDJ rearranged pre-B-cell receptor: VpreBλ5/μu heavy chain mature B cell: IgM plus IgD small pre-B cell: VJ rearranged
What happens to an immature B cell that encounters and is specific for self antigen? - Answer Continued rearrangement of light-chain genes.
Where in the lymph node would most of the follicular dendritic cells be? - Answer B cell area
Which of the following pertains to the fate of immature B cells with specificity for univalent self antigens?
All of the following cell-surface glycoproteins are expressed by double-negative thymocytes undergoing maturation in the thymus except
Answer-CD -CD
T/F: Apoptotic T cells are ingested by medullary epithelial cells.-Answer False
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?-Answer A pre-T-cell receptor is assembled as a superdimer.
Which of the following represents a difference in the α:β T cell developmental pathway from that of B cells? (Select all that apply.) Their antigen receptors are derived from gene rearrangement processes. When the first chain of the antigen receptor is made it pairs with a surrogate chain. Cells displaying self-reactive antigen receptors are induced to undergo apoptosis. MHC molecules are needed to promote passage through the developmental pathway.
T/F: T-cell receptor rearrangements share many features with immunoglobulin rearrangement, including the use of the RAG-1 and RAG-2 genes. - Answer True
T/F: The expression of the pre-T-cell receptor is required to terminate β-, γ-, and δ-chain rearrangements. - Answer True
The human thymus begins to involute as early as one year after birth. This is achieved by the deposition of ___ that previously represented thymocytes. - Answer involution; fat
Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is caused by a defect in - Answer a transcription factor that regulates tissue-specific gene expression in the thymus
Double-negative thymocytes initiate rearrangement at the _____ locus/loci before all other T-cell receptor genes. - Answer β, γ, and δ.
Healthy individuals have approximately ____ of CD4 T cells compared with CD8 T cells. - Answer twice the number
The function of negative selection of thymocytes in the thymus is to eliminate - Answer autoreactive thymocytes
Thymocytes that are not positively selected - Answer make up about 98% of developing thymocytes and die by apoptosis in the thymic cortex
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.)
- The positive selection of either of the T-cell receptors to MHC molecules of the thymic epithelium - One of the T -cell receptors will be functional while the other most probably will be nonfunctional. - If either T -cell receptor binds strongly to self-peptides presented by self-MHC molecules, the thymocyte will undergo negative selection.
Which of the following statements regarding positive selection is true? - Answer T-cell receptor editing is associated with positive selection.
Which of the following was one of the contributors that helped to activate the naive T cell? - Answer dendritic cells
Which of the following is characteristic of an activated dendritic cell as it arrives in the lymph node? - Answer bears highly elaborated finger-like processes called dendrites
Which of the following is expressed on immature dendritic cells in the skin prior to their activation? - Answer Toll-like receptors
Activated T cells express _____, which binds to B7 with 20 times higher affinity than CD28 and leads to _____ of T-cell activity and proliferation - Answer CTLA4; suppression.
All of the following are part of the central supramolecular activation complex (c-SMAC) except
Naive lymphocytes homing to lymphoid tissue use _____ to bind to CD34 and GlyCAM- on high endothelial venules - Answer L-selectin
TH2 response which delivers mycobacteria into the body.
Many cytokine receptors are associated with cytoplasmic protein kinases called _____, which become activated when the cytokine receptors bind to their respective cytokines.
Signal transducers and activators of transcription (STATs) are _____ that are phosphorylated by _____-Answer transcription factors; JAKs
Which of the following is a feature of regulatory T cells (Treg)? (Select all that apply.) Treg express CD8 and control effector cells by inducing apoptosis. Treg express high levels of CD25 (IL-2 receptor α chain) and secrete pro-inflammatory cytokines such as IFN-γ.
- Treg function requires physical association between Treg and their target cells. • Treg presumes the interaction and activation of naive T cells by interacting with dendritic cells in the secondary lympho id tissue. • Treg secrete TGF - β and suppress effector T-cell function. - Answer - Physical association between Treg and their target cells is mandatory for Treg function.
Which of the following is produced by CD8 T cells? Coalston Answer IFN-γ
Which of the following statements is/are not true about CD8 T cells?
effector CD8 cells require co-stimulation for killing target cells.
A B cell's sensitivity to antigen can be enhanced 1000-10,0000-fold by _________ Answer simultaneously ligating the B-cell receptor and co-receptor
Naive B cells search for specific antigen displayed by follicular dendritic cells in primary follicles. Naive T cells, however, search for specific antigen presented by _________ Answer dendritic cells
The process which drives an increase in antibody affinity for antigen is called _________ Answer affinity maturation
Which of the following is FALSE about FDCs?
Which of the following is not a function of antibodies? They neutralize pathogens by masking their surface They are molecular adaptors that bridge together the pathogen and phagocyte surfaces They exert toxic effects directly They serve as opsonins mediate phagocytosis They activate complement fixation Answer They exert toxic effects directly Which of the following statements is TRUE about the mechanism of B cell activation? a. Individuals with DiGeorge syndrome do not have a thymus so they do not produce any
Which of the following is characteristic of FcRn? Choose all that apply. a. It binds to monomeric IgA in acidified endocytic vesicles. b. It transports IgG out of the blood into tissue across the endothelium. c. It resembles an MHC class II molecule in its structure. d. It protects IgA from degradation by plasma proteases. -Two molecules of FcRn bind to each Fc region.
The name given to the process involving receptor-mediated transport of macromolecules from one side of a cell to the other is - Answer transcytosis
The symptoms of allergy and asthma are induced after cross-linking of IgE antibody on FcεRI receptors found on the surface of ____. (Select all that apply.)
To mount the most effective antibody response that results in the synthesis of
high-affinity antibodies, which of the following must occur? (Select all that apply.)
Of the following which antibody is passively transferred from mother to child via breast milk? -Answer dimeric IgA
Which of the following is indicative of a mast cell that has just undergone antigenic activation? -Answer lack of prepackaged granules
Antibody-dependent cell-mediated cytotoxicity (ADCC) is carried out by _____ after cross-linking of IgG1 or IgG3 antibodies on _____ receptors - Answer NK cells; FcγRIII
Complexes of IgG bound to soluble multivalent antigens can activate the classical pathway of complement, resulting in the deposition of _____ on the complex, targeting it for endocytic uptake by cells bearing _____ - Answer C3b; CR1 and Fc receptors
IgM is uniquely good at fixing complement because it ____ - Answer has five binding sites for C1q
ITAMs are found on _____. - Answer the cytoplasmic tails of Igα and Igβ
A number of forms of B-cell tumor have been treated with rituximab, an anti-CD monoclonal antibody that exerts its effect via a mechanism termed ______ and involving the participation of NK cells - Answer antibody-dependent cell-mediated cytoxicity
Which of the following is not a characteristic of secreted mucins
In addition to M cells, _____ can capture pathogens directly from the lumen of the gut. - Answer dendritic cells
Laboratory animals reared in gnotobiotic conditions _____ - Answer lack normal gut microbiota
M cells, unlike dendritic cells, _____. - Answer do not process and present their antigen to naive T cells.
Mucosae of a healthy intestinal tract _____. (Select all that apply.)
The vast population of microbes that make up the gut microbiota playing a major role in food processing are known as _____ - Answer commensal microorganisms
Unlike secreted mucins, membrane mucins _____ - Answer are not cross-linked by disulfide bonds
Which of the following describe M cells in the gut? (Select all that apply.)
Which of the following pairs is mismatched? Choose all that apply.
it will recirculate through all mucosal tissues, including respiratory and gastrointestinal mucosae
Intracytoplasmic bacteria in enterocytes of the gastrointestinal tract are detected by ____. Response NOD proteins
Secretory IgA and _____ can bind to the poly-Ig receptor and be transported into the lumen of the gut or across other mucosal surfaces - Answer pentameric IgM.
Secretory IgA binds to pathogens in all of the following locations except the ____.
Secretory IgA is best described as _____ - Answer a non-inflammatory immunoglobulin that restricts the passage of antigens across mucosal surfaces
The cytokine influencing eosinophil development and function during helminth infections is _____ - Answer IL-5.
The dominant immunoglobulin synthesized at mucosal surfaces is _____ - Answer IgA
Which of the following is not an activity associated with secretory IgA and secretory IgM in mucosal secretions?
confines commensal microbes to gut lumen controls population size of commensal microbes. - Answer complement fixation
Which of the following is not associated with the mechanism by which B cells produce secretory IgA in breast milk? J chain MAdCAM- αE:β 7 poly-Ig receptor CCR transcytosis. - Answer αE:β 7
Which of the following types of immune response are most effective in clearing helminthic infections of the gastrointestinal tract? (Select all that apply.) production of IgG2 antibodies production of IgE antibodies complement fixation eosinophil activation antibody-dependent cell-mediated cytotoxicity IFN-γinduced production of mucus TH1-derived cytokines. - Answers - production of IgE antibodies eosinophil activation antibody-dependent cell-mediated cytotoxicity
IgM compensates for the secretory IgA deficit seen in selective IgA deficiency because IgM can be secreted from mucosal tissues by utilizing the identical receptor responsible for its transcytosis. - Answer IgM.