Production of large quantities of human immunoglobulin in the ascites of athymic mice: implications for the development of anti-human idiotype monoclonal antibodies

Abstract

Human-murine hybridomas, generated by fusion of human CLL cells with non-Ig-secreting murine myeloma NS-1, and secreting the IgM kappa expressed on the CLL cell surface, were grown in the peritoneal cavity of doubly pristane-primed nude mice to produce large quantities of highly concentrated human IgM kappa for the development of anti-idiotype monoclonal antibodies. Although the hybridomas secreted only 0.8 to 1.5 micrograms/ml/10(6) cells in tissue culture, they produced 8 to 12 ml of ascites from two mice containing 1.7 mg/ml of human IgM. Partial purification was then easily accomplished by euglobulin precipitation. Two weekly injections of 100 micrograms of this material into BALB/c mice resulted in the development of both anti-idiotypic and anti-human IgM antibodies. This system overcomes the major hurdle of generating sufficient quantities of the human idiotypic Ig to immunize and screen for specific murine antiidiotypes, and provides the material to produce these therapeutically promising reagents rapidly for clinical trials. This is, to our knowledge, the first report of a human Ig produced in mouse ascites.