Question

CD4 antigen is absent on

• A. B-cells
• B. T-cells
• C. Macrophage cells
• D. Gamma-delta T cells

Hint:

CD4 is primarily expressed on helper T-cells, and is absent from B-cells, gamma-delta T-cells, and macrophages.

Answer 1

The Correct Option is A

Step 1: Understand the role of CD4 antigen.
The CD4 antigen is a surface glycoprotein expressed primarily on helper T-cells. It assists in immune responses by binding to MHC class II molecules on antigen-presenting cells, facilitating T-cell activation and coordination of the adaptive immune response.

Step 2: Evaluate which cells express CD4.

• B-cells: Do not express CD4. They are identified by markers such as CD19 and CD20 and are mainly involved in antibody production.
• T-cells: CD4 is expressed on helper T-cells (a subset of T-cells). These are central to activating other immune cells.
• Macrophage cells: While macrophages interact with CD4+ T-cells, they do not express CD4 themselves.
• Gamma-delta T-cells: These T-cells have a distinct receptor and do not express CD4.

Step 3: Conclusion.
The CD4 antigen is absent on B-cells. Therefore, the correct answer is Option (1): B-cells.