Exam 3: B cells

Question 1

Which of the following statements is correct?

Answer 1

The kappa light-chain genes rearrange before the lambda light-chain genes.

Question 2

Which of the following cell-surface markers differentiates hematopoietic stem cells from other cell constituents in the bone marrow?

Answer 2

CD34

Question 3

The consequence of allelic exclusion at the immunoglobulin loci ensures that _____.

Answer 3

B cells express antigen receptors of a single specificity and homogeneous B-cell receptors bind more effectively to antigens

Question 4

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

Answer 4

VDJ is successfully rearranged and µ(mu) heavy chain is made

Question 5

Which of the following is not paired with its correct complement?

Answer 5

Large pre B-cell stage: constitutive expression of RAG-1 and RAG-2 proteins

Question 6

A defect in which of the following proteins blocks B-cell development at the pre-B-cell stage, resulting in almost no circulating antibodies in individuals with this defect?

Answer 6

Bruton tyrosine kinase (Btk)

Question 7

Which of the following would occur after the production of a functional mu chain as a pre-B-cell receptor?

Answer 7

RaG proteins are degraded
Chromatin structure of heavy-chain locus is recognized to prevent gene rearrangement
Transcription of RAG 1 and RAG 2 genes ceases
There is allelic exclusion of a second mu chain
All of the above IS ANSWER

Question 8

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

Answer 8

The mu chain is assembled w/ Vpre-lambda5

Question 9

An important advantage of having two gene loci (kappa and lambda) for the light chain is ________.

Answer 9

That the likelihood of a successful rearrangement of light-chain genes increases

Question 10

The latest stages of late pro-B-cell development are recognized by the association of a surrogate light chain with a mu chain. The surrogate light chain is composed of _______.

Answer 10

VpreB and lambda5

Question 11

Immature B cells develop into B cells in the _______________.

Answer 11

Secondary lymphoid organs

Question 12

All hematopoietic stem cells express ___________.

Answer 12

CD34

Question 13

A developing B cell unable to generate a productive rearrangement on any of the four light-chain loci will undergo _____________.

Answer 13

Apoptosis

Question 14

In which location would plasma cells not be present?

Answer 14

Afferent lymphatic vessels

Question 15

Which of the following is a characteristic of B-2 cells?

Answer 15

They are located primarily in the secondary lymphoid organs

Question 16

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

Answer 16

CCL19 : lymph-dendritic cells
	CXCL13: follicular dendritic cells
	CCL21: stromal cells of secondary lymphoid tissues
	ALL OF THE ABOVE 
is the answer

Question 17

Immunological tolerance in the B-cell repertoire is called _______ tolerance when it develops in primary lymphoid organs, and _______ tolerance when it is induced outside the bone marrow.

Answer 17

Central; peripheral

Question 18

When producing monoclonal antibodies, why is it important to use as a fusion partner a myeloma cell that is unable to produce its own immunoglobulin?

Answer 18

To ensure that the antibodies are homogenous and able to male strong bivalent attachments to multivalent antigens

Question 19

Which of the following pertains to the fate of immature B cells that have specificity for univalent self-antigens?

Answer 19

The cells acquire a state of unresponsiveness called Anergy

Question 20

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

Answer 20

Two-thirds of these IgD antibodies possess kappa light chains

Question 21

All of the following events occur within germinal centers except:

Answer 21

B cells are activated by CD4 helper T cells

Question 22

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

Answer 22

Myc

Question 23

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

Answer 23

Lack N nucleotides
Possess polyspecificity for bacterial polysaccharide antigens
Arise early in embryotic development preceding development of majority of subset B cells
Have little to no IgD on the cell surface
ALL OF THE ABOVE

Question 24

Receptor editing occurs _____.

Answer 24

In bone marrow to establish self-tolerance of the B-cell repertoire

Question 25

All of the following participate in signal transduction in developing B cells except:

Answer 25

Terminal deoxynucleotidyl transferase (TdT)

Question 26

Negative selection of developing B cells ensures that ___________.

Answer 26

B-cell receptors that bind to normal constituents of the body do not emerge

Question 27

Plasma cells have all the properties listed except ______________.

Answer 27

Rapidly proliferate in secondary lymphoid follicles

Question 28

The circulatory route through a lymphoid tissue for both immature B cells and mature B cells that do not encounter specific antigen is:

Answer 28

bloodstream –> HEV of lymphoid cortex –> primary lymphoid follicle –> efferent lymphatic vessel