What does alexine mean?
Alexine is a noun with two distinct lives. In its scientific sense, it names a heat-labile substance present in normal blood serum that cooperates with antibodies to destroy bacteria and other foreign cells — a role that late nineteenth-century immunologists, including researchers such as Nuttall and Bordet, observed long before the mechanism was understood. Because this activity was later shown to depend on a whole system of serum proteins, the older single-substance terminology gave way to the modern term 'complement', and 'alexine' survives mainly in historical accounts of immunology. Independently, Alexine exists as a feminine given name, a variant of Alexandra found chiefly in French-speaking regions. The word derives ultimately from the Greek verb alexein, meaning 'to ward off' or 'to defend', the same root behind words like alexipharmic and alexiteric, which describe antidotes against poison. Today, meeting the word usually means reading old scientific literature or encountering someone's name.
A heat-labile substance in normal blood serum that acts together with antibodies to destroy bacteria and other foreign cells; historically termed alexine and now known as complement.
"Bordet demonstrated that the alexine in fresh serum was essential for the lysis of red blood cells."
This sense is obsolete in contemporary immunology, having been replaced by 'complement'.
A feminine given name, a variant of Alexandra.
"Alexine was delighted to learn her name shared a root with the ancient Greek word for defense."
Most commonly encountered in French-speaking regions.
Rarely used; the plural appears only in older immunological texts discussing multiple such serum substances.
"Early papers sometimes referred collectively to the alexines of different sera."
Before scientists settled on the name 'complement', they called the blood's bacteria-killing substance 'alexine' — literally, from the Greek for 'to ward off'.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of alexine
Alexine comes from the Greek verb alexein, meaning 'to ward off, defend, or protect', combined with the chemical suffix '-ine'. The term was adopted in late nineteenth-century immunology to describe the protective, bacteria-killing property of fresh blood serum. The same Greek root underlies related words such as alexipharmic and alexiteric, which refer to antidotes against poisons, and it also appears in the personal names Alexander and Alexandra. As immunological understanding advanced, the singular 'alexine' was replaced by the pluralistic concept of 'complement'.
Related word forms
How alexine is actually used
The immunological sense of alexine is largely obsolete; modern textbooks and research literature use 'complement' exclusively, so encountering 'alexine' today usually signals either a historical text or the given name.
Easily confused with alexine
An alexine defends the body by destroying foreign cells, whereas a toxin is a poisonous substance produced by living organisms.
Alexa is a modern feminine given name unrelated to the immunological term alexine, despite their similar spelling.