Infusion of tumor-infiltrating lymphocytes into a cancer patient demonstrates which type of immunity?

• A. Active immunity
• B. Adoptive immunity
• C. Passive immunity
• D. Natural immunity

Answer: (B)

Adoptive immunity is achieved by transferring immune components prepared outside the body into the patient. In tumor-infiltrating lymphocyte therapy, lymphocytes are taken from the patient's tumor, expanded and activated in culture, and then reinfused. These activated T cells directly recognize tumor antigens and attack the cancer cells once inside the patient, providing immunity through the transferred cells themselves rather than by the patient mounting a response on their own.

This differs from active immunity, where the patient's own immune system is primed in vivo to respond and form memory, and from natural immunity, which refers to the body's baseline defenses without such cellular transfers. The infused cells are a targeted cellular therapy, making this a clear example of adoptive immunotherapy.