Immunohistochemical identification of CA125 and the F(ab')2 fragments of the murine monoclonal antibody OC125 in ovarian cancer tissue.

Benign and malignant tissue samples of 19 ovarian cancer patients who received an intravenous infusion of radiolabelled F(ab')2 fragments of OC125 were examined for expression of CA125 and the cellular location of the injected antibodies. CA125 could be detected by immunohistochemistry in 47 of 71 biopsies containing cancer cells, but not in 258 biopsies with benign tissue. F(ab')2 fragments were found in 34 of these 47 biopsies. The diffuse intracytoplasmic staining pattern seemed to indicate that the injected antibodies had crossed the membranes of the cancer cells. Since the antibody could not be detected in benign tissues, further applications of OC125 for diagnostic and therapeutic purposes seems to be justified.