Genetically Stable Human Hybridomas Secreting Tumor-Reactive Human Monoclonal IgM

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Abstract
Human lymphocytes obtained from regional draining lymph nodes of patients with cancers of the cervix, kidney, prostate, and vulva were immortalized by polyethylene glycol-mediated somatic cell hybridization with either human UC 729–6 or murine P3-NS-1-Ag4–1. Four reactive human IgM-secreting hybridomas, termed CLNH5, MHG7, VLN1H12, and WLNA67 were isolated and characterized, Hybrids obtained by fusions with UC 729–6 have remained tetraploid for over 18 months, have doubling times from 25–35 hours, and have continuously secreted approximately 0.5–5.0 μg IgM/106 cells/ml per day. MHG7, a mouse-human hybrid, required subcloning every 4–6 months to maintain human IgM secretion. Binding of these human monoclonal antibodies (MoAbs) against a panel of cell lines was assessed by an enzyme-linked immunoassay (EIA). CLNH5 reacted with carcinomas of the cervix, lung, and vulva. MHG7 reacted with carcinomas of the prostate, stomach, and vulva. VLN1H12 reacted with carcinomas of the cervix, lung, prostate, stomach, and vulva. WLNA6 reacted strongly with a carcinoma of the lung. All four human MoAbs failed to react by EIA with hematopoietic cells or normal fibroblast cell lines. The data suggest that regional draining lymph nodes of cancer patients have been primed to produce antibodies against antigens associated with tumor cells and that UC 729–6 served as a genetically suitable vector for the capture and immortalization of these Ig-secreting B lymphocytes.