Alloantibodies

Part of speech: noun

Definitions

1. These specific antibodies develop when one individual's immune system detects and responds to the foreign antigens present in another individual of the same species
2. Such antibodies are generated as a result of the immune response to differing genetic antigens found in a genetically different individual of the same species
3. These particular antibodies arise when the immune system identifies and reacts to antigens from another organism of the same species that differ genetically

Etymology: Alloantibodies are a plural form, so the key story is in the parts of the word. "Allo-" comes from the Greek "allos," meaning "other" or "different," and it is the same prefix found in "allergy" and "allopathy." Attached to "antibody," it names immune proteins that react against cells belonging to another individual of the same species, rather than against invading microbes. The second element, "antibody," is the older and more familiar piece, built from "anti-," meaning "against," and "body" in the sense of a protein molecule. Combining the two gives a term that describes an antibody directed at a foreign version of a tissue or blood cell. Its use is most common in medicine, where it matters in blood transfusion and organ transplantation, because a recipient's immune system can produce these proteins against donor cells that carry markers it does not recognise as its own.