Novel approach to construction of human "myeloma analogues" for production of human monoclonal antibodies

Establishment of human Ig producing heterohybridomas by fusion of mouse myeloma cells with human lymphocytes derived from peripheral blood, bone marrow, spleen, lymph node, and synovial fluid. Effect of polyclonal prestimulation and cryopreservation

50 fusion experiments were carried out to analyse heterohybridization efficiencies on mouse myeloma cells of the P3 X63 Ag8/653 line with human lymphocytes derived from peripheral blood, bone marrow, lymph node, spleen or synovial fluid. We found higher yields of growing and human Ig-producing hybridoma lines when lymphocytes from spleen or lymph node were fused. Although primary hybridomas could be established from fusions with bone marrow-derived cells, only in nine out of 1616 initially seeded wells was Ig production registered. Four fusions using immune cells from synovial fluid were made without success. Independently of the source of lymphocytes pokeweed mitogen (PWM) prestimulation had no enhancing effect on the percentage of wells with cell growth and this did not alter the IgM:IgG ratio in primary hybridomas (9:1), although cells from all compartments used here (with the exception of bone marrow cells) could be stimulated with PWM to produce both IgG and IgM in cultures. Cryopreserved lymphocytes from different sources could be used for fusions with comparable results registered for the fresh material.

The high efficiency, human B cell immortalizing heteromyeloma CB-F7. Production of human monoclonal antibodies to human immunodeficiency virus

This paper describes the construction of a new heteromyeloma cell line designated CB-F7. The cell line was derived from xenogeneic somatic cell hybridization between normal human B lymphocytes and the murine HAT-sensitive P3X63Ag8/653 cell line. CB-F7 cells were characterized by rapid cell growth (doubling time about 16 h) and high cloning efficiencies in culture medium supplemented with 10% or 5% fetal calf serum, respectively. The karyotype of the cells consists of about 75-78 chromosomes as well as two chromosomal fragments. Fusions of the cells with human peripheral blood cells resulted in approximately 2-6 clones per 10(5) seeded lymphocytes. Furthermore, the cells are ouabain resistant and therefore suitable for fusions with EBV-transformed lymphoblastoid cell lines. Using CB-F7 as the parental cell line a number of specific human mAb producing hybrids were established. For the first time, we describe here the generation of hybrids secreting human monoclonal antibodies to human immunodeficiency virus (HIV). Two monoclonal antibodies of IgG type and one of IgM type reacted with the major core protein p25 and one IgG antibody reacted with the transmembrane protein gp41.

Effects of culture media on murine hybridomas: definition of optimal conditions for hybridoma viability, cellular proliferation, and antibody production

Different cell culture media were compared for their ability to support and promote the growth of stable hybridoma cell lines derived from three commonly used parental murine myelomas. Supplemented Dulbecco's modified Eagle's media (DMEM) and RPMI 1640 media were studied. The DMEM-based media were found to support greater numbers of cells for longer time periods than were the RPMI 1640-based media. Aminopterin supplemented medium was shown to be significantly less effective in supporting hybridoma reproduction and viability than medium without aminopterin. Antibody levels were directly related to cell concentration and viability regardless of the medium used for the hybridoma culture. An optimally formulated DMEM-based medium is suggested as the medium of choice for hybridoma propagation and maintenance.

The construction and use of a human-mouse myeloma analogue suitable for the routine production of hybridomas secreting human monoclonal antibodies

A human-mouse myeloma analogue termed HMMA2.11TG/O was constructed by fusion of the mouse myeloma cell line P3x63Ag8.653, a mutant derivative of MOPC21, with bone marrow mononuclear cells from a patients with IgA myeloma. The HMMA2.11TG/O cell line is resistant to 6-thioguanine and ouabain and sensitive to HAT. The cell line secretes no detectable immunoglobulin and has a hybrid karyotype and cell surface phenotype. An average fusion efficiency for growth of hybridomas of 1/17,000 fused cells was obtained in fusions with human peripheral blood mononuclear cells (PBM), Pokeweed Mitogen (PWM) stimulated PBM, and Epstein-Barr Virus (EBV) transformed polyclonal B cell lines. Over 75% of hybrids secrete detectable immunoglobulin and the cloning efficiency of the hybrids at 1 cell/well averages 25%. Antibody secreting cloned hybridoma cell lines were obtained by fusion directly with PBM from an immunized volunteer and by fusion with in vitro, secondarily immunized, EBV transformed polyclonal cell lines. Five hybridomas secreting human monoclonal IgM anti-tetanus antibodies and 2 secreting human monoclonal IgG anti-tetanus antibodies were selected and cloned from 6 fusions performed specifically for anti-tetanus antibody. Immunoglobulin and antibody secretion by cloned hybrids has been stable for 5-10 months at present. Immunoglobulin and antibody secretion in routine cultures passaged every 3-4 days has been 8-42 micrograms/ml. This human-mouse myeloma analogue should prove useful for the routine production of human monoclonal antibodies.