Establishment, Molecular Rescue, and Expression of 123AV16-1, a Tumor-reactive Human Monoclonal Antibody

Abstract The human monoclonal antibody (mAb) 123AV16-1 was generated by Epstein-Barr virus transformation of peripheral blood lymphocytes from a colorectal patient undergoing active specific immunotherapy with an autologous tumor cell- Bacille Calmette-Guerin vaccine. Direct immunohistochemical staining of tumor and normal pairs of tissues indicated that this human IgA1, λ2 mAb preferentially reacted with colon tumor epithelium. To generate a recombinant derivative of this Epstein-Barr virus-transformed cell line, we isolated the expressed complete heavy and light chain genes by a novel strategy and cloned them into modified pSV2-neo and pSV2-gpt expression vectors. The recombinant 123AV16-1 human mAb was expressed in both a murine myeloma and a human-murine heteromyeloma and was secreted as both monomers and dimers. The recombinant 123AV16-1 mAb expressed by both cell lines reacted with human colon tumor xenografts in a manner similar to the mAb derived from the Epstein-Barr virus-transformed cell line, indicating that the antibody specificity was not appreciably altered during the molecular rescue, cloning, or expression.