Question

The germinal centre of the lymph node mainly consists of

• A. T cells
• B. B cells
• C. Plasma cells
• D. Macrophages

Hint:

In a lymph node, the outer cortex contains follicles dominated by B cells, the paracortex is the T-cell dependent zone, and the medulla contains cords of antibody-secreting plasma cells.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Lymph nodes are secondary lymphoid organs structured into an outer cortex, paracortex, and inner medulla.
The outer cortex contains lymphoid follicles, which are the primary sites for humoral immune responses.
Upon activation by antigen-presenting cells, primary follicles develop into secondary follicles containing germinal centers.
Detailed Explanation:
The germinal center is a specialized microenvironment that forms within lymphoid follicles during an active immune response.
It is composed predominantly of rapidly proliferating B lymphocytes (centroblasts and centrocytes).
Inside the germinal center, these B cells undergo somatic hypermutation of their immunoglobulin genes and selection by follicular dendritic cells (FDCs).
This process leads to affinity maturation and immunoglobulin class switching, optimizing the antibody response.
While helper T cells (specifically follicular helper T cells, or Tfh) and macrophages (tingible body macrophages) are present within the germinal center to assist in selection and clear apoptotic cells, the overwhelming majority of cells participating in this microenvironment are B cells.

Step 2: Final Answer:
The germinal centers of lymph nodes mainly consist of B cells.