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GATE 2023 BT – Question 18

General Biology · Immunology: Cellular and humoral immunity, antibody diversity and function, monoclonal antibodies, T-cell and B-cell development, memory · 1 mark · Multiple choice

Which one of the following is required for the development of B-cells in the bone marrow?

  1. Stromal cells
  2. Dendritic cells
  3. Kupffer cells
  4. NK cells

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Correct answer: (A) Stromal cells

Explanation

B cells develop in the **bone marrow**, where they depend on the microenvironment of **stromal cells**. These cells provide:
- contact signals through adhesion molecules (such as VCAM-1 and VLA-4),
- cytokines, notably **IL-7** and the chemokine **CXCL12**, and
- the stem cell factor (SCF) needed for early progenitors.

Dendritic cells present antigen, Kupffer cells are liver macrophages and NK cells are innate killers; none of them forms the B-cell niche. Answer **stromal cells** (A).