Embryoglycan is a high molecular weight
glycopeptide, found abundantly in the cell surface of F9, stem cell clone derived from mouse
teratocarcinoma. Many differentiation-associated
antigens and receptors for
lectins have been shown to be carried by
embryoglycan. Furthermore,
antibodies reacting with
embryoglycan have been detected in the sera of patients with ovarian
germ cell tumor. We investigated anti-
embryoglycan antibodies in the sera of patients with
uterine cervical cancer, considering the possibility of the appearance of
embryoglycan-like
antigen accompanied by malignant changes in the uterine cervix. Reaction between the patients' sera and
embryoglycan (or F9 cells) was assayed by Farr's assay and an indirect immunofluorescence method. Among the patients with
uterine cervical cancer (
squamous cell carcinoma), 16 of 61 cases (26%) were positive in invasive cases, whereas early cases (14 cases) were all negative. Cases of benign ovarian
tumor (23 cases), uterine
myoma (25 cases) and 50 normal volunteers were all negative. The
antigenic determinant of
embryoglycan was found to be alpha-galactosyl residue since
alpha-galactosidase-treated
embryoglycan lost the activity to bind these
antisera. However, the antigenic structure of alpha-galactosyl residue was shown to be distinct from the
antigenic determinant of erythrocytes blood type B, but to some degree cross reacted with it, in an absorption test. These results indicate that an unusual alpha-galactosyl residue carried by
embryoglycan is expressed on at least some
uterine cervical cancer cells. Furthermore the immune system of patients produces
antibodies reacting with the alpha-galactosyl residue of
embryoglycan. It would be possible to use this method in monitoring patients' specific immune response.