Which of the following is an example of passive immunotherapy?

Passive immunotherapy involves the administration of pre-formed antibodies to provide immediate immune support or enhancement, rather than stimulating the patient’s immune system to produce its own antibodies. Monoclonal antibodies exemplify this process, as they are laboratory-made molecules engineered to target specific antigens on cancer cells or other disease-causing agents. When these monoclonal antibodies are given to a patient, they directly bind to the targets, marking them for destruction by the immune system or blocking their function.

In contrast, cancer vaccines, adjuvants, and immune checkpoint inhibitors work by stimulating or enhancing the patient's own immune response. Cancer vaccines are intended to provoke an immune response against cancer cells, while adjuvants enhance that response or promote a stronger reaction to both vaccines and other treatments. Immune checkpoint inhibitors target regulatory pathways in the immune system to release the brakes on immune responses, thereby allowing the body to mount a more effective attack against cancer cells. These approaches rely on engaging and amplifying the body’s own immune mechanisms rather than directly supplying antibodies, which differentiates them from passive immunotherapy.