Development of new immunoradiometric assay for CA 125 antigen using two monoclonal antibodies produced by immunizing lung cancer cells

• Published in: Annals of nuclear medicine 1988-12, Vol.2 (2), p.73-79
• Main Authors: Kunimatsu, M, Endo, K, Nakashima, T, Awaji, T, Saga, T, Watanabe, Y, Kawamura, Y, Ohta, H, Koizumi, M, Sakahara, H
• Format: Article
• Language: English
• Subjects: Adenocarcinoma - immunology; Antibodies, Monoclonal; Antigens, Tumor-Associated, Carbohydrate - analysis; Female; Humans; Immunoradiometric Assay - methods; In Vitro Techniques; Lung Neoplasms - immunology; Ovarian Neoplasms - immunology; Uterine Neoplasms - immunology
• ISSN: 0914-7187; 1864-6433
• DOI: 10.1007/BF03164948

CA 125 is an antigen associated with non-mucinous epithelial ovarian cancer, which is defined by OC 125 antibody developed by immunizing ovarian cancer cells. We have produced two monoclonal antibodies, 130-22 and 145-9, by using the human lung adenocarcinoma cell line PC-9. Both 130-22 and 145-9 antibodies recognized CA 125 antigen. However, the binding sites seemed to be separate from those of OC 125. Testing by 9 immunoradiometric assays (IRMA), using different combinations of the 3 monoclonal antibodies 130-22, 145-9 and OC 125 demonstrated that the best standard curve for detecting CA 125 could be obtained by a "simultaneous sandwich" assay based on a mixture of 125I-labeled OC 125 and 130-22 or 145-9 coated beads. One-step IRMA, using 130-22 as a tracer and 145-9 as an immunoadsorbent, also showed good reproducibility and sensitivity for measuring CA 125. Antigens were detectable in the culture supernatants of PC-9 cells and 5 of 6 ovarian cancer and endometrial adenocarcinoma cells. These results indicate that one-step IRMA using 130-22 and 145-9 is useful for detecting CA 125 antigen.