[Galactosyltransferase isozyme II (GT-II) as a new tumor marker for ovarian cancers--especially for clear cell carcinoma].

Serum levels of galactosyltransferase (GT) and its isozyme (GT-II), which transfers galactose from UDP-galactose to N-acetylglucosamine etc., in gynecologic malignancies, were assayed. GT activity was assayed with UDP-[3H] galactose and ovalbumin as substrate, and GT-II was assayed by selectively removing GT-II from serum by immunoabsorption with immobilized monoclonal antibody 3872, followed by assay of bound GT activity. GT was not specific for cancer, but GT-II was positive in 74% of the ovarian cancer patients, and remarkably high serum levels were observed in mesonephroid cancers, indicating its possible usefulness as a new tumor marker. Immunohistochemical staining revealed that GT-II was localized on the cell surface and in the cytoplasm, suggesting its production by tumor cells.