What is the process called when a lymphocyte proliferates and differentiates?

• A. Immune activation
• B. Clonal selection
• C. Antigen presentation
• D. Phagocytosis

Answer: (B)

The process when a lymphocyte proliferates and differentiates is known as clonal selection. This occurs when a specific lymphocyte is activated by an antigen that matches its receptor. Once activated, the lymphocyte undergoes clonal expansion, meaning it replicates itself to produce many identical cells. These clones then differentiate into either effector cells, which carry out the immune response, or memory cells, which provide long-term immunity by remaining in the body and responding more rapidly upon subsequent encounters with the same antigen.

Clonal selection is a critical mechanism in the adaptive immune response, allowing for a tailored immune response against specific pathogens while generating a lasting memory for quicker future responses. This nuanced process is distinct from immune activation, which can be a broader term encompassing various aspects of the immune response. Additionally, antigen presentation and phagocytosis refer to different processes involved in the immune response, but they do not specifically capture the concept of lymphocyte proliferation and differentiation.