3/2/17 GERMAN B Cell Development TEST #2 Flashcards by Cutler Frandsen

T/F B cells are stockpiled an not constantly replaced

False

-B cells are not stockpiled and constantly replaced

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What is the Phase one in the B Cell life?

-Generation of diverse and clonally expressed B-cell receptors in bone marrow

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What is Phase 2 in the B cell life?

-Alteration, elimination or inactivation of B-Cell receptors that bind to components of the human body (negative selection)

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What is Phase 3 in the B cell life?

-(occurs in the bone marrow and periphery) Promotion of a fraction of immature B cells to become mature B cells in secondary lymphoid tissues (Positive selection)

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What is Phase 4 in the B cell life?

-Recirculation of mature B cells between lymph, blood, and secondary lymphoid tissues (searching for infection)

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What is Phase 5 in the B cell life?

-Activation and clonal expansion of B cells by pathogen derived antigens in secondary lymphoid tissues

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What is Phase 6 in the B cell life?

-Differentiation to antibody-secreting plasma cells and memory B cells in secondary lymphoid tissue (Attacking infection)

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What is the half life of a B-cell once it matures?

-50-100 days

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What does Phase 3.5 to Phase 6 occur in the B cell life?

-Periphery

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What class of antibody is an immature B cell?

IgM (1st)

- IgD (2nd)

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When you have an antigen activated B lymphoblast what occurs?

Isotype switching that leads to antibody-secreting plasma cells
Clonal expansion

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What is the first stage in B cell development that you get rearrangement of the heavy chain?

-Early pro-B cell

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What two things occur in the Pro-B cell stages that are involved in rearrangement

Junctional Diversity

- Genetic Recombination

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What is the checkpoint between the Pro B cell and the Pre B cell?

-A Functional heavy chain

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What is the checkpoint between the pre B cells and immature B cell?

-Functional light chain

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What chain is rearranged in the pre B-cell stage?

-Light chain

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T/F Stromal cells express adhesion molecules and growth factors

True

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T/F B cell receptor expression does not change with progression through developmental stages

False

-It changes with progression

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If you don’t produce a functional heavy chain (pro-B cell) what happens to the B cell?

-It dies

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What happens with the RAG proteins in the early pro-B cell?

-RAG proteins are activated

What happens with the regions on the heavy chain in the early PRO-B cell stage?

-Heavy chain D and J segments joined

T/F In the early pro-B cell the rearrangement occurs on both chromosomes

True

In the late Pro-B cell what heavy chain segments join?

-Heavy chain V and DJ segments join

T/F Pre-B Cell Receptor signaling causes the transition from Pro to Pre B cell

True

What does the VDJ produce?

-Pre-BCR

Where is the Pre-BCR expressed?

-ER

What does the Pre-BCR allow the heavy chain to do?

-interact to the Ig-Alpha and Ig-Beta

When the heavy chain interacts with what does it pass a checkpoint clearance?

-Ig-Beta

When you have Ig-Beta signaling you have three things that occur, What are they?

- Turns off RAG proteins - Initiates cell division - Allelic exclusion

What is allelic exclusion?

-It is when a functional heavy chain is produced by only one chromosome

What does the Late pro-B cell become?

-Large pre-B cell

What is responsible for initiating light chain rearrangement?

-Pre-B cells

When you go from the Large pre-B cell to the small pre-B cell what occurs?

- Cell division - RAG genes reactivated - Unique recombination

How many recombination attempts are possible per chromosome in the light chain?

-4-5

What are the two types of chromosome genes on the light chain?

- Lambda | - Kappa

After you have the heavy chain and light chain rearrangement what must you have to not experience apoptosis?

-A B-cell receptor via (Ig alpha and Ig Beta)

If an immature B-cell doesn't react with a self antigen what happens?

-It is released into the blood

What are the two types of tolerance of B-cells

- Central tolerance (occurs in the Bone marrow) | - Peripheral tolerance (occurs outside the bone marrow)

What are the three fates of a B cell that bound self cells?

- Light Chain reorganization to try and become functional - Apoptosis - Anergy (Still alive but shut down all signaling and activating process)

Where do B-cells mature?

-Secondary lymphoid tissues (spleen, lymph nodes, GALTS)

How do immature B cells enter into they lymphoid tissues?

-High Endothelial venule

What two chemokines attract B cells into the lymph node?

- CCL 21 | - CCL 19

Interactions with what cells drives the maturation of immature B cells?

-Follicular dendritic cells

What two things are involved in positive selection for a B cell?

- Lymph node localization | - BAFF signaling

Where are B cells activated?

-Lymphoid tissues

When the B cell interacts with T cells and becomes activated what occurs?

-Migration, secondary lymphoid follicle formation, and clonal expansion

What occurs in the Germinal centers?

-Plasma cell production and antibody secretion

What do Dysfunctional B cell developments cause?

-Cancers