Fundamentals of B-cell biology Which of the following statements about B lymphocytes is FALSE?

Introduction / Context:
B-cell development, tolerance, and effector functions are core immunology topics. Distinguishing where B cells mature and how they respond helps avoid common exam traps that confuse B-cell and T-cell pathways.

Given Data / Assumptions:

• B cells and T cells arise from hematopoietic stem cells but mature in different primary lymphoid organs.
• Class switching changes isotype, not antigen specificity.
• Self-reactive immature B cells are negatively selected in bone marrow.

Concept / Approach:

B cells develop and undergo V(D)J recombination and central tolerance in the bone marrow. T cells develop in the thymus (T for thymus). After activation, B cells may class switch (e.g., IgM to IgG, IgA, or IgE) under T-helper and cytokine signals, and differentiate into plasma cells to secrete soluble antibodies. Thus, any statement sending B-cell development to the thymus is false.

Step-by-Step Solution:

Verification / Alternative check:

Clinical observations (e.g., agammaglobulinemia due to bone marrow B-cell defects) and thymic aplasia syndromes (e.g., DiGeorge) affecting T, not B, cells corroborate the distinct maturation sites.

Why Other Options Are Wrong:

• Class switching (A) is correct and cytokine-driven.
• Surface immunoglobulin/BCR expression (C) is fundamental.
• Central tolerance/apoptosis (D) is accurate.
• Plasma cell differentiation (E) is a hallmark effector function.

Common Pitfalls:

• Mixing up B-cell vs. T-cell maturation sites due to mnemonic confusion.

Final Answer:

Bone marrow stem cells migrate to the thymus and develop into B cells.