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GATE 2023 BT Q.18: solution and answer

GATE 2023 · BTQ.18 · 1 mark · MCQ

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

  1. (A)

    Stromal cells

  2. (B)

    Dendritic cells

  3. (C)

    Kupffer cells

  4. (D)

    NK cells

See the question in the paper
GATE 2023 BT question 18Tap to open full size

Answer and solution

ANSWER

The answer is (A): stromal cells.

Official answer: ASource: Official answer key, GATE 2023 BT (IIT Kanpur)

  1. B-cells develop from hematopoietic stem cells in the bone marrow, passing through pro-B, pre-B and immature B-cell stages before they leave for the periphery.

  2. Each stage depends on contact with bone marrow stromal cells (reticular cells, osteoblast-lineage cells and endothelial cells). These cells supply stem cell factor (SCF), the chemokine CXCL12, IL-7 and adhesion molecules such as VCAM-1.

  3. (A) Stromal cells: correct. They form the niche that drives B-lymphopoiesis. Without IL-7 and CXCL12, development stalls at an early progenitor stage.

  4. (B) Dendritic cells: wrong. They are antigen-presenting cells that activate T-cells in peripheral lymphoid organs. They are not part of the marrow niche for B-cell development.

  5. (C) Kupffer cells: wrong. These are liver-resident macrophages that clear particles and pathogens from the blood. They are not part of the B-cell niche.

  6. (D) NK cells: wrong. They are innate cytotoxic lymphocytes that kill virus-infected and tumour cells. B-cell maturation does not need them.

  7. Hence the answer is (A).

KEY IDEA

B-lymphopoiesis in the bone marrow depends on the stromal cell niche, which supplies IL-7, CXCL12, SCF and adhesion molecules. Dendritic cells, Kupffer cells and NK cells play no part in it.

WATCH OUT FOR

Choosing dendritic cells because they are linked to antigen presentation and B-cell responses. That role is in peripheral lymphoid organs. It is not a requirement for B-cell development in the marrow.

From the GATE 2023 BT paper. Every question of this paper · Download the full paper · All 7 Adaptive immunity questions, with notes

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