Which term is used for substances that induce an immune response?

The term that describes substances capable of inducing an immune response is "antigens." Antigens are typically proteins or molecules found on the surface of pathogens, such as bacteria and viruses, as well as on pollen, certain medications, and even transplanted tissues. When the immune system detects these antigens, it triggers a response, which may include the production of antibodies to help neutralize or eliminate the threat.

Antibodies, while critical in the immune response, are the products made by B-cells in response to antigens and act to target and neutralize those antigens. Pathogens refer to any microorganisms that can cause disease, including bacteria, viruses, fungi, and parasites, but they are not substances themselves that induce an immune response. Allergens are a specific type of antigen that can cause allergic reactions, but they do not encompass the full range of substances that can elicit an immune response.