Which statement best describes clonal expansion?

Which statement best describes clonal expansion?

• A. Activation of random lymphocytes by antigen
• B. Death of lymphocytes after activation
• C. Proliferation of activated clones to form effector and memory cells
• D. Migration of lymphocytes to thymus

Answer: (C)

Clonal expansion is the rapid proliferation of lymphocytes that have already recognized their specific antigen. After a single activated lymphocyte binds its antigen, it divides many times to produce a large population of identical cells that all share the same antigen specificity. This creates both effector cells to fight the current infection and memory cells for quicker responses in the future. The other ideas don’t describe this growth of a specific clone: random activation isn’t antigen-specific, death after activation describes contraction rather than expansion, and migration to the thymus isn’t part of the expansion process (the thymus is where T cells mature, not where activated cells multiply).

Clonal expansion is the rapid proliferation of lymphocytes that have already recognized their specific antigen. After a single activated lymphocyte binds its antigen, it divides many times to produce a large population of identical cells that all share the same antigen specificity. This creates both effector cells to fight the current infection and memory cells for quicker responses in the future. The other ideas don’t describe this growth of a specific clone: random activation isn’t antigen-specific, death after activation describes contraction rather than expansion, and migration to the thymus isn’t part of the expansion process (the thymus is where T cells mature, not where activated cells multiply).