[Anti-embryoglycan antibodies detected in sera of patients with uterine cervical cancer].

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.