Week 6 - Development of B Lymphocytes

These flashcards cover key concepts related to the development of B lymphocytes, their maturation process, and mechanisms to prevent self-reactive cells.

What is the source of B cells in the body?

Bone marrow stem cells.

List the six phases of B cell development.

1) Acquisition of antigen receptors and rearrangement, 2) Negative selection, 3) Positive selection, 4) Patrolling for pathogens, 5) Activation and clonal expansion, 6) Differentiation into effector and memory cells.

What happens during Phase 2 of B cell development?

Negative selection occurs, eliminating B cells that bind to self-antigens.

What is the role of stromal cells in B cell maturation?

Stromal cells assist with B cell maturation, interacting through adhesion molecules and producing growth factors like IL-7.

What is allelic exclusion in B cell development?

Allelic exclusion is the mechanism that results in B cells having one functional immunoglobulin by preventing the formation of additional immunoglobulins.

During which phase do B cells rearrange their heavy chain genes?

During pro-B cell development.

What is receptor editing and when does it occur?

Receptor editing is the process where self-reactive B cells rearrange their light chains to become non-self-reactive, and it occurs when B cells encounter self-antigen.

What signals an immature B cell to become anergic?

Binding of soluble self-antigen by the immature B cell triggers the B cell to make IgD and become unresponsive to the antigen.

What are the primary lymphoid organs involved in B cell development?

Bone marrow is the primary lymphoid organ where B cells develop.

What are memory B cells and what is their significance?

Memory B cells are high-affinity, isotype-switched antibodies that persist throughout a person's lifetime and can be easily activated upon re-exposure to their antigen.

What percentage of immature B cells have effective light chain rearrangement?

85% of immature B cells have a successful light chain rearrangement.

How do B cells circulate after leaving the bone marrow?

B cells circulate through blood, secondary lymphoid tissues, and lymph.

What is the outcome if B cells fail to pass the checkpoints in bone marrow?

B cells that do not pass the checkpoints undergo apoptosis.

Describe the journey of B cells after maturation in secondary lymphoid tissues.

B cells enter lymph nodes, interact with antigens, and either proliferate and differentiate into plasma cells or leave the lymph node as naïve B cells.

What are the two types of tolerance that prevent self-reactive B cells from causing autoimmune diseases?

Central tolerance in primary lymphoid organs and peripheral tolerance in peripheral lymphoid organs.

What is the role of IL-7 in B cell development?

IL-7 is a growth factor produced by stromal cells that is essential for B cell maturation.

What happens during Phase 5 of B cell development?

B cells are activated by pathogens, leading to proliferation and clonal expansion.

What do mature naive B cells express on their surface?

Mature naive B cells express both IgM and IgD on their surface.