Anaphylaxis
The body usually forms antibodies in response to invasion by a foreign material.
The medical term for a foreign substance is "antigen." An antigen is any substance that the immune system identifies as foreign and triggers an immune response.
Immune System
Antigen
A response of the body to an invasion of foreign substances is inflammation. The immune system will also produce more white blood cells and send them to the site of the infection.
Antigenan·ti·gen/ˈantijən/Noun:A toxin or other foreign substance that induces an immune response in the body, esp. the production of antibodies.
Antigen
a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies.
A foreign substance is a substance that doesn't belong somewhere. A piece of glass or splinter is a foreign substance that people get in their body.
A foreign substance is a substance that doesn't belong somewhere. A piece of glass or splinter is a foreign substance that people get in their body.
A foreign substance is some substance or material that does not belong where it is, such as a rock in your cereal.
Depending on the exact response, the substance is generally called a pathogen, yet more specifically depending on the nature of the response and origin of the substance, could be an antigen, allergen, carcinogen, etc.