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Immunology Exam Q&A: B-Cell and T-Cell Development Study Guide, Exams of Advanced Education

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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2024/2025

Available from 05/15/2025

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MCMP 422 - Exam 2 Questions And Verified Answers
All hematopoietic stem cells express - Answer CD34
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 λ5
Which of the following cell-surface markers identifies hematopoietic stem cells from
among the other bone marrow cell constituents? - Answer CD34
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?
- The κ light-chain genes rearrange before the heavy-chain genes.
- The κ light-chain genes rearrange before the λ light-chain genes.
a. The λ light-chain genes rearrange before the heavy-chain genes.
b. The λ light-chain genes rearrange before the κ light-chain genes.
c. The μ heavy-chain genes rearrange first and then the λ light-chain genes rearrange
Answer d. The κ light-chain genes rearrange before the λ light-chain genes.
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MCMP 422 - Exam 2 Questions And Verified Answers

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?

  • The κ light-chain genes rearrange before the heavy-chain genes.
  • The κ light-chain genes rearrange before the λ light-chain genes. a. The λ light-chain genes rearrange before the heavy-chain genes. b. The λ light-chain genes rearrange before the κ light-chain genes. c. The μ heavy-chain genes rearrange first and then the λ light-chain genes rearrange Answer d. The κ light-chain genes rearrange before the λ light-chain genes.

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?

  • Autoreactive B cells are eliminated before the energy expenditure required to rearrange a functional light-chain gene. - The energy spent to genera te a functional heavy chain is not wasted because an inability to generate a functional light chain. • RAG gene expression is turned off, which in turn sends a signal to terminate the light- chain rearrangement. • A polyclonal population of immature B cells is generated that express the same μ chain but a unique light chain. About 85% of small pre-B cells will go on to mature into immature B-cells - Answer Autoreactive B cells are deleted before the energy expenditure required to rearrange a functional light-chain gene

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

  • immature B cell: μ heavy chain plus λ or κ light chain on surface - Answer - pre-B-cell receptor: VpreBλ5/μu heavy chain
  • mature B cell: IgM plus IgD
  • immature B cell: μ heavy chain plus λ or κ light chain on surface.
  • after encounter with foreign antigen in secondary lymphoid organs
  • in mature B cells
  • to establish self-tolerance of the B-cell repertoire
  • to show an excess of IgM over IgD on the surface of mature B cells. - Answer - in the bone marrow
  • to determine self-tolerance of the B-cell repertoire

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?

  • The cells become unresponsive in a state called anergy.
  • IgD remains in the cytosol.
  • IgD on the cell surface cannot activate the B cell following its binding to self antigen.
  • The cells have a much longer life-span than mature B cells.
  • The cells die by apoptosis. - Answer - The cells acquire a state of unresponsiveness called anergy.
  • IgD on the cell surface fails to activate the B cell when bound to self antigen.

All of the following cell-surface glycoproteins are expressed by double-negative thymocytes undergoing maturation in the thymus except

  • CD
  • CD
  • CD127 (IL-7 receptor)
  • CD

- CD1A

- CD4-

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 cells do not rearrange their antigen-receptor genes in the bone marrow. - Answer - MHC molecules are needed to allow passage past the developmental checkpoint.
  • T cells do not rearrange their antigen-receptor genes in the bone marrow.

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.

  • One of the T-cell receptors may be autoreactive but escape negative selection because its peptide antigen is present in tissues other than the thymus.
  • Subsequent gene rearrangements may give rise to a γ:δ T-cell receptor. - Answer - Engaging either of the T-cell receptors on MHC molecules of the thymic epithelium will result in positive selection.
  • One of the T-cell receptors will be functional while the other most probably will be non-functional.
  • If either T-cell receptor binds strongly to self-peptides presented by self-MHC molecules, the thymocyte will be negatively selected.
  • One of the T-cell receptors may be autoreactive but escape negative selection because its peptide antigen is present in tissues other than the thymus.

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

  • CD4 or CD
  • ICAM-
  • CD
  • T-cell receptor
  • PKC-θ. - Answer ICAM-

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.

  • The milder form of leprosy has high amounts of IL-2 and IFN-γ produced by responding T cells. - Answer In tuberculoid leprosy, the patient mounts a TH1 response that eliminates the mycobacteria from the body.

Many cytokine receptors are associated with cytoplasmic protein kinases called _____, which become activated when the cytokine receptors bind to their respective cytokines.

  • Answer JAKs.

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.

  • Through interaction with dendritic cells in secondary lymphoid tissue, Treg prevent the interaction and activation of naive T cells.
  • Treg produce TGF-β and inhibit effector T-cell 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?

  • CD8 T cells have only one effector function and that is cytotoxicity. More stringently than naive CD4 T cells, the naive CD8 T cell requires co-stimulatory activity. To kill target cells, an effector CD8 cell also requires co-stimulation. The most potent antigen-presenting cell to naive CD8 T cells is the dendritic cell. Response The

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?

  • They store antigens in the form of immune complexes on their dendrites
  • They send survival signals to B cells binding to them
  • They are originated from hematopoietic stem cell
  • They store antigens for years
  • They are found in primary follicles of lymph nodes - Answer They are originated from hematopoietic stem cell

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

  • They provide a stable depository of intact antigens able to bind to B-cell receptors. They form dendrites and thus have a large surface area. They internalize immune complexes through CR2 receptor cross-linking. They are producers of cytokines which induce B cells to proliferate and become centroblasts. Answer They provide a stable depository of intact antigens able to bind to B-cell receptors. They form dendrites and thus have a large surface area.

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.

  • Answer It transports IgG out of the blood into tissue across endothelium. -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.)

  • basophils
  • eosinophils
  • macrophages
  • mast cells
  • neutrophils. - Answer - basophils
  • eosinophils
  • mast cells

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.)

  • recognition of thymus-independent (TI) antigens -isotype switching
  • B cells' increased expression of TLR
  • affinity maturation
  • decreased expression of CD40 by B cells -Answer - isotype switching
  • affinity maturation

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

  • compete with pathogenic variants for nutrients and space
  • convert toxic substances to benign derivatives
  • degrade plant fibers to make their nutrients available
  • produce enzymes that degrade proteins
  • produce key metabolites
  • stimulate the formation of gut-associated lymphoid tissue. - Answer produce enzymes that degrade proteins

Which of the following is not a characteristic of secreted mucins

  • glycosylated cysteine residues
  • multiple repetitive sequence motifs
  • viscous matrix that is stabilized by disulfide bonds
  • interact with positively charged effector molecules
  • products of seven genes in humans
  • expressed in different mucosal tissues. - Answers contain glycosylated cysteine residues

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.)

  • have a large number of activated T and B cells
  • harbor T cells bearing a very wide diversity of antigen specificities
  • contain intraepithelial lymphocytes
  • have large numbers of resident neutrophils
  • are populated with both α:β and γ:δ effector T cells. - Answer - have a large number of activated T and B cells
  • contain intraepithelial lymphocytes
  • are inhabited by both α:β and γ:δ effector T cells.

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.)

  • They acquire their name from mucus cells.
  • These are located in the dome of a Peyer's patch.
  • They transport antigens and pathogens across the lymphoid tissue to the luminal side of the gut mucosa through a process called transcytosis.
  • These are guarded against digestive enzymes by a thick layer of glycocalyx and also an overlying layer of mucus.
  • They, themselves, do not take part directly in antigen processing or presentation. Where are M cells located? Answer They are located in the dome of a Peyer's patch. -They themselves do not participate directly in antigen processing or presentation.

Which of the following pairs is mismatched? Choose all that apply.

  • appendix: large intestine
  • mesenteric lymph nodes: urogenital tract
  • effector compartment: induction of adaptive immune responses
  • adenoids: base of nose

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 ____.

  • endosomes of an M cell
  • lamina propria
  • lumen of the gut
  • blood
  • Peyer's patches. - Answer blood

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?

  • toxin neutralization
  • complement fixation binds to mucin via disulfide bonds

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.