Generation of human-mouse hybridoma secreting human IgM class anti-neocarzinostatin antibody and its application to hybrid hybridoma.

Abstract

antibodies are required for the therapy of diseases to avoid undesirable side effects.9' Recently, we developed human-mouse hybridomas secreting human IgM class anti-ricin or anti-diphtheria toxin antibodies by the transformation of human peripheral blood lymphocytes (PBLs) with Epstein-Barr virus (EBV), followed by cell fusion between the transformed cells and mousemyelomaSP2/O2.10) With these hybridomas, we established hybrid hybridomas that secreted IgM class human bifunctional antibodies as a model experiment.ll' However, the affinity of the secreted hybrid IgM to diphtheria toxin was lower than that to ricin. One possibility for this is the low expression of immunoglobulin polypeptide genes to diphtheria toxin in the hybrid hybridoma, due probably to improper technique for the generation of the hybrid hybridoma. The previous method10' used actinomycin-D treatment of one hybridoma line to fuse with another 6-thioguanineresistant hybridoma line. Wesupposed that the actinomycin-D treatment in the fusion procedure were responsible for the lower affinity to diphtheria toxin of the produced bifunctional antibody, because Kobayashi et al. 12) reported that a T-cell hybridoma that had been generated by the actinomycin-D method tended to lose its capability of secreting some lymphokines. To solve this problem, we Fig. 1. Scheme for Generation of Hybrid Hybridoma Secreting Anti-neocarzinostatin/Anti-diphtheria Toxin Bifunctional Antibody.