Development of human–human hybridoma from anti-Her-2 peptide–producing B cells in immunized NOG mouse

Numerous monoclonal antibodies have been developed for the purpose of medical treatments, including cancer treatment. For clinical application, the most useful are human-derived antibodies. In this study, we tried to prepare designed antigen-specific antibodies of completely human origin using immunodeficient mouse. Nonobese diabetic/severe combined immunodeficient/IL-2 receptor γ null mouse (NOG) mouse was used to reconstitute the human immune system with umbilical cord blood hematopoietic stem cells (CB-NOG mouse) and to prepare human-derived Her-2-epitope–specific antibodies. Hybridoma lines were prepared by fusing the human myeloma cell line Karpas707H. Serum of immunized NOG mouse contained human-derived immunoglobulin M (IgM) antibodies specific for a short peptide sequence of 20 amino acids, including the epitope peptide of apoptotic Her-2 antibody CH401. Hybridoma lines were successfully prepared with spleen B cells obtained from the immunized CB-NOG mouse. One of these cell lines produced human IgM against the epitope peptide that can recognize surface Her-2 molecule. We could produce human-derived IgM antibody against Her-2 epitope peptide in CB-NOG mouse, succeeding in generation of human hybridoma-secreting IgM against a given peptide.