Human chorionic gonadotropin--like material: presence in normal human tissues.

With the use of radioreceptor assay for gonadotropin and a beta-chain radioimmunoassay for human chorionic gonadotropin (hCG), we have been able to demonstrate the presence of hCG-like material in all normal human tissues tested. This activity was completely absorbed by a hCHG-antibody affinity column and was demonstrated to have altered carbohydrate content by studies showing this material did not bind to concanavalin A (con A)-Sepharose affinity columns. In identical studies greater than 90% of placental hCG was bound to con A. However, if placental hCG is rendered carbohydrate free it also does not bind to con A. It is known that carbohydrate-free hCG is cleared rapidly from the circulation and thus possesses little or no biological potency in vivo. Accordingly, we hypothesize: (1) that this hCG-like material in normal tissues has the protein structure of hCG but does not possess the carbohydrate moieties of placental hCG and probably has little or no bioactivity in vivo and (2) that the trophoblastic cell is not unique in its ability to synthesize hCG but has developed the ability to glycosylate hCG, transforming a ubiquitous cellular protein into a hormone, hCG might better be called human cellular gonadotropin.