Final answer:
Antigens are large signaling molecules not normally found in the body that the immune system recognizes as foreign, prompting an immune response including antibody production.
Step-by-step explanation:
In the context of your immune system, it is important to be able to identify antigens: large signaling molecules not normally found in the body. An antigen is a foreign or "non-self" macromolecule that the immune system may respond to by forming antibodies, which leads to the destruction of cells bearing the antigens. The process of distinguishing between self and non-self molecules is crucial for both the innate and adaptive immune responses, where major histocompatibility complex (MHC) molecules play a key role in this recognition.
This distinction between self and non-self enables the immune system to effectively handle potential threats, such as pathogens, while avoiding autoimmune reactions where the body would mistakenly attack its own cells. When foreign antigens are detected, the immune system can initiate various responses, including producing antibodies that specifically target the antigen for neutralization or destruction.