DISCUSSION
Several investigators have considered the difficulties involved in obtaining adequate supplies of mouse antibodies. The use of Freund's adjuvants to induce ascites has been employed successfully by several laboratories ; however, this method suffers from inconsistency, as in in some instances little ascitic fluid is obtained. Herrmann and Engle have used Sarcoma 180 cells to produce hyperimmune ascitic fluid in mice. The rapid proliferation and the relatively high degree of virulence of this neoplasm, however, produced early deaths, thereby limiting the usefulness of this procedure. The development of a relatively non-virulent subline of this tumor (Sarcoma 180/TG), resulted in cell line yielding large quantities of ascites fluid. Indeed, in one experiment each animal produced greater than 40 ml of purified ascitic fluid. Thus, a 180/TG cells have been successfully employed to produce antibodies against several arboviruses, proteins (albumin and globulin), mixture of proteins (human serum) and a cellular antigen (sheep erythrocytes). The antibody obtained at 14 days is not mercaptoethanol sensitive and hence probably not of the polymeric (19S) type. In general, the antibody titers of the ascitic fluids prepared by this method were comparable to those of the sera. Both the volumes of asciticic fluid and the titers of antibody were higher in CD-l mice than in C57Bl/6J mice. The tumor cells had been maintained in the CD-l strain for many generations before their use in the C57BI/6J mice; thus, host adaptation of neoplastic cells may be one reason for the difference in response.
The use of mice to prepare hyperimmune fluid offers several advantages: 1) the animals are readily available; 2) they require considrably less space than do larger animals; 3) their use is relatively economical and 4) the technique is important for the preparation of homologous antibodies to viruses which either require mice as the host, or for which mice have been chosen as the desired host in which to maintain the virus.