Antikörper

Antikörper is a German compound: anti- (against, from Greek) and Körper (body, from Latin corpus). Paul Ehrlich, the German immunologist, used the term in the 1890s to describe the substances in blood serum that could neutralize toxins and kill bacteria. Ehrlich's 'side-chain theory' proposed that cells had receptor molecules on their surface, and that these receptors could be released into the blood to attack specific pathogens. He called the released receptors Antikörper — bodies that fight against.

English translated the German compound directly: anti + body = antibody. The word entered English medical literature in the early 1900s. It was one of many immunological terms coined during the golden age of microbiology, when Ehrlich, Emil von Behring, Kitasato Shibasaburo, and others were racing to understand how the body fights disease. Ehrlich shared the 1908 Nobel Prize with Élie Metchnikoff for their work on immunity.

The actual structure of antibodies was not determined until the 1960s, when Gerald Edelman and Rodney Porter independently worked out the Y-shaped protein structure. An antibody is a Y-shaped protein with two binding sites that can attach to a specific antigen (a molecule on the surface of a pathogen). The immune system produces billions of unique antibodies, each targeting a different antigen. The word Antikörper — a fighting body — turned out to be a protein with arms.

The COVID-19 pandemic made antibody a household word. Antibody tests, monoclonal antibodies, antibody levels — the immunological vocabulary of the 1890s became dinner table conversation in 2020. A German compound from the age of diphtheria entered everyday English during the age of coronavirus.