from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A protein in blood serum that participates in the body's immune response by working in conjunction with the alternative pathway of the complement system.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A protein in human serum that complements part of the immune system


Probably pro-1 + Latin perdere, to destroy; see perdition + -in.
(American Heritage® Dictionary of the English Language, Fourth Edition)


  • The activation through the classical pathway requires C1q, the alternative pathway requires C3b, properdin, and serum factors B and D; and the lectin pathway requires binding carbohyrdate residues on the surface of the bacteria similar to C1q.

    Confirmation Bias and ID

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