alexin

English

Ultimately from German Alexine, coined by Hans Buchner in 1891 from the Ancient Greek ἀλέξειν (aléxein).[1]

alexin (plural alexins)

(biochemistry, dated) A protective substance that exists in the serum or other bodily fluid and is capable of killing microorganisms; complement.
- 1929, Thomas Wolfe, Look Homeward, Angel, New York: Scribner, Part One, Chapter 1, p. 3,
  The seed of our destruction will blossom in the desert, the alexin of our cure grows by a mountain rock […]

protective substance that exists in the serum

Buchner H (23 June 1891), “Kurze Uebersicht über die Entwicklung der Bacterienforschung seit Naegeli's Eingreifen in dieselbe [Brief overview of the development of bacteriology since Naegeli's involvement in it]”, in Münchener Medizinische Wochenschrift‎ (in German), volume 38, issue 25, pages 435–437, issue 26: 454–456, quote from p. 437: “Es handelt sich demnach um Eiweisskörper einer neuen Kategorie, die mit irgend welchen bisher bekannten sich nicht identificieren lassen, und die man am besten deshalb mit einem neuen Namen, etwa als » Alexine« (d. h. Schutzstoffe, von ἀλέξειν abwehren, schützen) bezeichnet. [So it's a matter of protein of a new type, which cannot be identified with any [protein] which [has been] known until now, and which one therefore designates best with a new name, perhaps as "alexine" (i.e., protective stuff, from ἀλέξειν to fight off, defend).]”