The study of antibodies and antigens dissociated from the immune complexes extracted from ovarian carcinoma ascitic fluid

Ovarian cancer-associated antibodies recovered from ascites: their use for the isolation of ovarian cancer-associated antigen to produce monoclonal antibodies

Immune complexes (ICs) were recovered from the ascites of a patient with stage IV endometrioid ovarian cancer by sequential precipitation with 33% saturated ammonium sulfate and 2.5% polyethylene glycol 6000 (PEG 6000), followed by affinity chromatography on protein A-Sepharose CL-4B. The IgG-containing ICs were dissociated using 8 M urea, separated by ion-exchange chromatography on Sephadex QAE-50, and subsequently analyzed for purity by immunoelectrophoresis (IEP) and radial immunodiffusion (RID). Recovered antibody was tested for reactivity by immunohistologic techniques against paraffin-embedded tumor tissue and acetone-fixed cell suspensions of epithelial tumors. The antibody which demonstrated ovarian cancer-associated activity was absorbed with antigen extracts of breast, colon, and lung cancers as well as keratin to reduce cross-reactivity. The absorbed endometrioid ovarian cancer-associated antibody (OCAAb) was used to produce an immunoadsorbent column for the recovery of tumor-associated antigens. A mouse monoclonal antibody designated FEN-1 was produced using this antigen-containing fraction, and preliminary screening has demonstrated ovarian tumor-associated reactivity. The use of autologous ICs as reagents for preparing tumor antigen-rich immunogens may provide a valuable tool in the search for tumor-associated antigens.

Detection of human ovarian tumor-associated antigens by antibodies isolated from ovarian carcinoma ascitic fluid

Ascitic fluid from patients with ovarian epithelial cancer contains large amounts of soluble immune complexes and is a potential source of antibodies and antigens associated with the tumor. The antibodies against tumor-associated antigens were purified from the ascitic fluids of patients with ovarian serous cystadenocarcinoma. These antibodies showed specificity toward ovarian epithelial cancer when tested against ovarian tumor cell lines and paraffin-embedded tissue sections of ovarian cancer. The antigens in sera of patients were separated from IgG and IgG complexes by affinity chromatography and the free antigens were isolated. With the antibodies purified from ascitic fluid, the levels of tumor-associated antigens in sera of 10 patients with serous cystadenocarcinoma and 12 control patients were detected by an enzyme-linked immunosorbent assay. The antigens in patients with ovarian epithelial cancer were 2 to 10 times higher than those in control patients. These studies demonstrate that the antibodies isolated from ascitic fluid detect the tumor-associated antigens on tumor cells as well as the shed antigens present in serum.