idioagglutinin

[ĭd′ē-ō-ə-glōōtn-ĭn]
n.
  1. An agglutinin that occurs in the blood of a person or animal without the injection of a stimulating antigen or without the passive transfer of antibodies.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.