B Cells

Where does B cell development begin

bone marrow, where immature B cells are formed

Where do B cells migrate

Immature B cells exit the bone marrow and travel to the lymph nodes and spleen.

Where do B cells mature

in the germinal center or B cell follicle of the lymph node and spleen.

Naïve status of B cells

B cells remain naive until they encounter their specific antigen.

B cell separation from bone marrow

Mediated by the interaction between integrin VLA-4 on the B cell progenitor and VCAM-1 on stromal cells

IL-7 signaling

Produced by bone marrow stromal cells, IL-7 promotes B cell development and eventual release from the bone marrow.

What happens to activated B cells in germinal centers?

Activated B cells undergo further differentiation, becoming either plasma cells or memory cells.

What are the two possible outcomes for B cells after differentiation in the germinal centers?

They become either plasma cells, which secrete antibodies, or memory cells, which provide long-term immunity.

What happens if light chain rearrangement fails in B cells?

B cells get a second chance to rearrange. If this fails, they are retained in the bone marrow and eventually undergo apoptosis.

What is central tolerance?

Central tolerance occurs in the bone marrow, where B cells are tested for self-reactivity.

What is peripheral tolerance?

Peripheral tolerance occurs outside the bone marrow, where self-reactive B cells are typically suppressed or eliminated.

What happens if B cells recognize univalent soluble self-antigens?

They become anergic, meaning they are unresponsive and unable to mount an immune response.

What are B1 cells?

B1 cells respond to bacterial polysaccharides, produce IgM, and can respond to antigens without T cell help.

What are B2 cells?

The more common B2 (Conventional Follicular) cells require T cell help to become activated.

Where does antigen presentation occur?

Antigen presentation happens in the lymph nodes, spleen, or Peyer’s patches.

What role do helper T cells play in antigen presentation?

Helper T cells (CD4) assist in antigen presentation, helping B cells differentiate into plasma cells or memory B cells.

What happens when an antigen is detected?

A germinal center forms at the follicle, leading to lymph node swelling and B cell differentiation and proliferation.

Where can plasma cells go after differentiation?

Plasma cells can either leave for the bone marrow or secrete antibodies into circulation.

How can tumors occur in relation to B cell differentiation?

Tumors can arise when B cell differentiation and development go wrong, leading to cancers like Burkitt’s lymphoma, Hodgkin’s lymphoma, and multiple myeloma

What is the genetic abnormality in Burkitt’s lymphoma?

Burkitt’s lymphoma involves the MYC gene and gene swapping between chromosomes 8 and 14

How are monoclonal antibodies used in cancer treatment?

Monoclonal antibodies are used to target specific antigens involved in cancer, aiding in therapy.

What is Rituxan used for?

Rituxan is an anti-CD20 therapy used to treat certain cancers, like non-Hodgkin’s lymphoma.

A patient is diagnosed with Burkitt’s Lymphoma, whichinvolves a translocation of chromosome 8 and chromosome 14. Which gene is most likely affected, leading to uncontrolled cell division?

MYC

A researcher is studying the function of Pre-B cells. They observe that heavy chain recombination is proceeding normally, but there is an issue with light chain rearrangement. What is the next likely step in the B cell development process?

The cell will rearrange the kappa chain followed by the lambda

chain.

A new drug is developed to block IL-7 signaling in bone marrow

stromal cells. What effect would this likely have on B cell

development?

Decreased release of progenitor B cells from the bone marrow

A patient is found to have B1 cells that are highly active. What

type of antigen is most likely responsible for this activation,

and what antibody is primarily produced by B1 cells?

Bacterial polysaccharides; IgM

During a laboratory experiment, an immature B cell interacts

with a multivalent self-antigen in the bone marrow. What is the

most likely fate of this B cell?

It will undergo receptor editing or apoptosis to prevent

autoimmunity

A mutation in the gene that regulates the expression of CD34

leads to a disruption in hematopoietic stem cell activity.

Which stage of B cell development would be most directly

affected?

Common lymphoid progenitor