What substance is produced by the body that inactivates antigens?

The substance produced by the body that inactivates antigens is an antibody. Antibodies are specialized proteins created by the immune system in response to foreign substances, known as antigens, which can include pathogens like bacteria and viruses. When an antigen enters the body, it is recognized as foreign, prompting the immune system to produce antibodies that specifically bind to these antigens. This binding can neutralize the antigen, mark it for destruction by other cells of the immune system, or prevent it from entering or damaging healthy cells.

The process of antibody production is a critical part of the adaptive immune response, allowing the body to identify and remember specific pathogens. This is why vaccination, which introduces a harmless part of an antigen to stimulate antibody production, is an effective way to protect against diseases.

While antigens are the target of antibodies, and cytokines are signaling molecules that help regulate the immune response, and pathogens are the harmful agents themselves, they do not function in the direct inactivation of antigens in the same manner as antibodies do.