The molar vesicle fluid contains the beta-core fragment of human chorionicgonadotropin

The human chorionic gonadotropin (hCG) p-core fragment (beta-CF) is a major molecular form of hCG beta subunit (hCG beta) immunoreactivity in the urin e of pregnant women and patients with trophoblastic disease. The majority o f evidence supports the fact that the P-CF is a degradative product of inta ct hCG and free hCG beta in the kidneys. We found a beta-CF-like substance in the fluid of molar vesicles from a patient with complete hydatidiform mo le. The molar fluid beta-CF (m beta-CF) was indistinguishable from the beta -CF in the patient's urine (u beta-CF) by immunoreactivity and by elution p rofile on gel chromatography. The binding study to lectins, however, showed that m beta-CF contains a carbohydrate moiety that differs from that of u beta-CF. Immunohistochemistry with anti-beta-CF antibody demonstrated a strong immun oreactivity in a large number of macrophages in the molar villous stroma. I n vitro incubation of intact hCG with peritoneal macrophages showed a slow increase of intact hCG in the cell cytosol with the appearance of beta-CF-l ike substance in the cell supernatant. In conclusion, the source of beta-CF in molar fluid is likely to be macrophages existing in the villous stroma. Thus macrophages may ingest intact hCG and act as a local regulator of gon adotropic hormones. (C) 2000 Harcourt Publishers Ltd.