A human monoclonal antibody HMD4 against ovarian carcinoma associated antigen

Lymphocytes from regional lymph nodes of patients with ovarian carcinoma were immortalized by fusing them with a nonsecreting cell line of murine myeloma (Sp2/0-Ag14). The fusion rate was 0-87.5%. By early cloning and recloning, a hybrid cell line, named HMD4, was established. It has stably secreted human IgG for more than 15 months. Chromosome analysis showed the characteristics of human-mouse hybridoma. The cells of HMD4 were injected into the abdominal cavities of nude mice and 2-3 weeks later large quantities of ascites were obtained. Human IgG of lambda light chain was detected and purified from the ascites. The specificity of HMD4 human McAb was tested by ABC or PAP immunoperoxidase stainings of paraffin-embedded tissue sections, cryostat sections, cell smears of various tissues and different cancer cell lines. 60.5% (26/43) of epithelial ovarian cancers was positive, while nonepithelial ovarian cancers, most cancers from other organs and almost all nonmalignant and normal tissues were negative. The molecular weight of the antigen recognized by HMD4 was 55 KDa determined by Western blotting. The problems of maintaining the IgG secreting function of human-mouse hybridoma and its screening were also discussed.