This lesson introduces how B lymphocytes develop and how their receptors recognize antigens. Understanding these foundations explains how B cells can respond to many different pathogens while limiting attacks against the body’s own tissues.
B cells originate from multipotent hematopoietic stem cells (HSCs) in the bone marrow. These cells progress through lymphoid stem-cell and lymphoblast stages. Unlike T-cell precursors, B-cell precursors remain in the bone marrow rather than traveling to the thymus to mature.
All flashcards
What is a naïve mature B cell?
A mature B cell that has not yet encountered the conditions needed to respond to its specific antigen.
How do positive and negative selection shape the developing B-cell population?
Positive selection retains cells with functional receptors; negative selection limits self-reactivity through deletion, receptor editing, or anergy.
Which immunoglobulins serve as B-cell receptors on naïve mature B cells?
Membrane-bound monomeric IgM and IgD.
How are B-cell receptor variable regions diversified?
Gene segments rearrange: V, D, and J in heavy chains; V and J in light chains.
How does antigen recognition differ between B-cell and T-cell receptors?
B-cell receptors bind accessible epitopes directly; T-cell receptors recognize protein epitopes presented by MHC molecules.
Quiz questions
What can provide the second activation signal in a T-independent B-cell response?Answer: Innate recognition of PAMPs by toll-like receptors or signals associated with complement.
What does linked recognition mean during a T-dependent B-cell response?Answer: A B cell presents a peptide from an antigen that a specific helper T cell also recognizes.
What changes during antibody class switching?Answer: The constant region changes while the variable region and antigen specificity are retained.
Compared with the primary response, what is characteristic of the secondary response to the same protein antigen?Answer: It has a lag of only a few days and produces substantially more IgG.
When does IgM typically peak during the primary antibody response?Answer: Around day 14, before IgG reaches its later peak.
Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.