Isolation of antibodies to HCG/LH from human sera

ANTIBODIES to gonadotrophin have previously been detected only in the sera of a few patients, mainly with endocrinological disorders1–4 or receiving hormone therapy, and antibodies reacting with trophoblast have been described in association with pregnancy5–8. We report here the presence of antibodies to human chorionic gonadotrophin (HCG) and luteinising hormone (LH) in normal human sera. These were found initially in pooled postpartum sera but sera from males, non-pregnant females, children and umbilical cord also contained antibodies which were predominantly IgG. HCG is a secretory product of trophoblast and forms an integral part of the trophoblast membrane9–12. Its distinction from human pituitary LH lies principally in the β chain where HCG has an additional C-terminal 30 amino acids13.