Characterization of an Established Mouse-Human Heterohybridoma and its Application for Production of (Mouse-Human)-Human Triple Hybridoma Secreting Human Immunoglobulin

We report the construction of a mouse-human (M-H) heterohybridoma by fusion of the murine myeloma cell line NS-1 and human spleen cells from a 17 week old fetus. The nonsecreting, cloned hybridoma cell line II was resistant to 8-azaguanine (8-AG) and sensitive to hypoxanthine, aminopterin and thymidine (HAT) medium. It grew rapidly in 8-AG containing medium (doubling time 20 hrs.), but did not grow in HAT medium or in non-serum medium. It had a high fusion frequency with human lymphocytes from regional lymph nodes. Five human chromosomes were retained stably for over 6 months by this cell line II. Nine (mouse-human)-human ((M-H)-H) triple hybridomas secreting human IgG 1 or IgM were established by the fusion of this parental cell line II and human lymphocytes from regional lymph nodes. Immunoglobulin secretion was stable and has been maintained for over 8-10 months without recloning in these hybridomas. Secretion of immunoglobulin varies from 2.1-3.0 μg/10⁶ cells/day, and these hybridomas contain from 3 to 16 human chromosomes, including No. 14. So, this M-H heterohybridoma II is an excellent useful parental cell line for the production of hybridomas secreting human immunoglobulin.