An albumin-like protein is the major secretory protein of ovarian epithelial cells in vivo and in vitro.

Contemporary experimental techniques were used to evaluate the protein secretion of ovarian epithelium. The protein composition of 14 ovarian cyst fluids (OCF) from either cystadenomas or cystadenocarcinomas, and conditioned media (CM) from seven ovarian carcinoma lines in culture, were analyzed by SDS-PAGE under reducing conditions, and Western immunoblots. The major protein common to all the above samples was a 65 kDa protein that, by densitometry, constituted between 43% and 77% of OCF protein and 19% and 38% of CM protein. By Western blot analysis, this band was immunologically related to human albumin. Moreover, immunoreactivity to albumin was demonstrated in ovarian epithelium in vivo. Ovarian epithelium synthesizes and releases an albumin-like protein that constitutes the major secretory protein. This may suggest an osmotic mechanism for cyst enlargement in ovarian cystadenomas.