Which immunoglobulin is found on the surface of B lymphocytes and is important in B cell activation?

• A. IgG
• B. IgE
• C. IgD
• D. IgA

Answer: (C)

Verified step by step guidance

1. Understand the role of B lymphocytes in the immune system: B lymphocytes (B cells) are responsible for producing antibodies and play a crucial role in adaptive immunity. They require activation to initiate antibody production.
2. Learn about immunoglobulins (antibodies): Immunoglobulins are proteins produced by B cells that help identify and neutralize pathogens. There are five main classes of immunoglobulins: IgG, IgA, IgM, IgE, and IgD, each with distinct functions.
3. Focus on IgD: IgD is a type of immunoglobulin found on the surface of immature B cells. It plays a critical role in B cell activation by acting as a receptor for antigens, which triggers the B cell to become activated and start producing antibodies.
4. Compare IgD with other immunoglobulins: IgG is the most abundant antibody in circulation and provides long-term immunity. IgA is found in mucosal areas and secretions like saliva and tears. IgE is involved in allergic responses. None of these are primarily involved in B cell activation like IgD.
5. Conclude that IgD is the correct answer: Based on its function as a receptor on B cells and its role in activation, IgD is the immunoglobulin associated with B cell activation.