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A. Discuss the importance of the bone marrow stroma for B-cell development. B.What would be the effect of anti-IL-7 antibodies on the development of B cells in the bone marrow,and at which stage would development be impaired? Explain your answer.

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.Bone marrow stromal cells provide the n...

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A plasma cell is characterized by which of the following features? (Select all that apply.)


A) It differentiates in the medulla of lymph nodes and the bone marrow.
B) It dedicates 10-20% of total protein synthesis to antibody production.
C) Levels of MHC class II molecules are elevated.
D) It undergoes extensive proliferation in germinal centers.
E) It produces secreted immunoglobulin instead of the membrane-bound form.

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of the following are associated with the development of Burkitt's lymphoma except


A) The expression of Myc protein is perturbed.
B) A chromosomal translocation involving a proto-oncogene and an immunoglobulin gene occurs.
C) Overproduction of the Bcl-2 protein prolongs the lifetime of B-lineage cells.
D) Cell division restraints on mutated B cells are lifted.
E) In addition to a chromosomal translocation event,mutations elsewhere in the genome are usually involved.

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What is the fate of an immature B cell that encounters and has specificity for self antigen?


A) If further heavy-chain and light-chain gene rearrangements are possible,it undergoes apoptosis.
B) Somatic hypermutation.
C) Decrease in production of IgD.
D) Continued rearrangement of heavy-chain genes.
E) Continued rearrangement of light-chain genes.

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A.Give three properties that distinguish B-1 cells from B-2 cells. B.Do you think that B-1 cells should be categorized as participants in innate immune responses or in acquired immune responses? Explain your rationale.

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A.Unlike conventional B-2 cells,B-1 cell...

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Which of the following statements about the IgD made by B cells of upper respiratory mucosa is not true?


A) These antibodies bind to airborne bacteria such as Haemophilus influenzae.
B) λ light chains are used almost exclusively by these IgD antibodies.
C) Two-thirds of these IgD antibodies possess κ light chains.
D) These IgD antibodies recruit basophils and induce the secretion of antibacterial peptides.

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Which of the following pertains to the fate of immature B cells that have specificity for univalent self antigens? (Select all that apply.)


A) The cells acquire a state of unresponsiveness called anergy.
B) IgD is retained in the cytosol.
C) IgD on the cell surface fails to activate the B cell when bound to self antigen.
D) The cells have a much longer life-span than mature B cells.
E) The cells die by apoptosis.

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Which of the following is characteristic of a large pre-B cell?


A) VDJ is successfully rearranged and μ heavy chain is made.
B) V-J is rearranging at the light-chain locus.
C) μ heavy chain and λ or κ light chain is made.
D) V is rearranging to DJ at the heavy-chain locus.
E) D-J is rearranging at the heavy-chain locus.

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Which of the following characterizes the B-1 cells that develop prenatally?


A) They lack N nucleotides.
B) They possess polyspecificity for bacterial polysaccharide antigens.
C) They arise early in embryonic development preceding the development of the majority subset of B cells.
D) They have little or no IgD on the cell surface.
E) All of the above.

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Individuals who fail to express functional Bruton's tyrosine kinase exhibit all of the following characteristics except


A) B-cell development is blocked at the immature B-cell stage.
B) They are usually male because the Btk gene is on the X chromosome.
C) They suffer from an immune deficiency known as X-linked agammaglobulinemia (XLA) .
D) Recurrent infections with extracellular bacteria are common.
E) They benefit from treatment with immunoglobulin infusions.

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Explain how B cells undergo the process of negative selection and indicate at which stage of development and at which location these events occur.

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Immature B cells that express receptors ...

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Multiple myeloma involves the unregulated proliferation of an antibody-producing plasma cell (myeloma cell)independently of antigen stimulation or T-cell help.Myeloma cells populate multiple sites in the bone marrow,where they produce immense quantities of monoclonal immunoglobulin as well as suppressing normal marrow function.Myeloma cells also synthesize and secrete excessive amounts of free light chains (known as Bence-Jones protein),which,because of their low molecular weight (~25 kDa)are excreted as free light chains in the urine. In a given patient the free light chains are both monoclonal and all are of either the κ or the λ type. A.Explain both of these observations. B.Why do you think patients with multiple myeloma are more susceptible than normal to pyogenic infections,such as pneumonia caused by Streptococcus pneumoniae or Haemophilus influenzae?

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A.In a normal response to infection,a di...

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Receptor editing occurs _____.(Select all that apply.)


A) in the bone marrow
B) after encounter with foreign antigen in secondary lymphoid organs
C) in mature B cells
D) to establish self-tolerance of the B-cell repertoire
E) to express an excess of IgM over IgD on the surface of mature B cells.

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What would be the consequence if terminal deoxynucleotidyl transferase (TdT)were expressed throughout the whole of small pre-B-cell development?

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N nucleotides would be added at the VJ j...

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The proto-oncogene _______ is associated with the development of Burkitt's lymphoma.


A) BCL-2
B) Myc
C) CD5
D) CD19
E) BTK.

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Immature B cells develop into B cells in the


A) subendosteum
B) bone marrow
C) thymus
D) blood
E) secondary lymphoid organs.

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When expression of _______ is turned off in small pre-B cells,the result is the presence of P nucleotides but an absence of N nucleotides in around 50% of light-chain genes.


A) Kit
B) CD19
C) TdT
D) Pax-5
E) RAG-1 and RAG-2.

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Large pre-B cells are characterized by which of the following?


A) They do not express CD19 at the cell surface.
B) Rearrangement of light-chain genes commences.
C) Nonproductive rearrangement of both heavy-chain loci has already occurred.
D) Allelic exclusion of the immunoglobulin light-chain loci has already occurred.
E) μ is assembled with VpreBλ5.

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You are going to use flow cytometry to determine the proportion of developing B cells in the bone marrow that are immature, anergic, or mature. You have three monoclonal antibodies specific for three different B-cell surface proteins. The first has specificity for the cell-surface protein CD19, which is expressed by all developing and mature B cells; the second is specific for the Fc region of IgD; and the third is specific for the Fc region of IgM. The antibodies are conjugated to three different fluorescent tags that can be detected and distinguished by the flow cytometer. A. Use histograms to show your analysis of CD19-positive cells and indicate which part of your histogram you would gate to analyze IgM and IgD expression. Indicate the gated population with an arrow. B. Using a two-dimensional dot plot, compare the expression of IgD and IgM of these gated cells, and say which of these populations represents (i) immature B cells, (ii) mature B cells, and (iii) anergic B cells.

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.Histogram.Your histogram should look li...

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Identify the mismatched pair of chemokine and the cells that secrete it.


A) CCL19: lymph-node dendritic cells
B) CXCL13: follicular dendritic cells
C) CCL21: stromal cells of secondary lymphoid tissues
D) All of the above are correctly matched.

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