A strategy for the production of human monoclonal antibodies reactive with lung tumor cell lines

Abstract

Epstein-Barr virus (EBV)-immortalized cell lines were established from lymphocytes derived from peripheral blood, draining lymph nodes, bone marrow aspirates, tumors, and pericardial effusions from lung cancer patients. Ten of these lines were cloned and screened against glutaraldehyde-fixed lung tumor cells for tumor-specific antibody production using an enzyme-linked immunosorbent assay. None of the 140 clones tested secreted specific antibody, suggesting that B-lymphocytes specific for tumor antigens are rare in lung cancer patients. The EBV lines from the lung cancer patients were then hybridized with a thioguanine-resistant, ouabain-resistant human B-lymphoblastoid fusion partner KR-4, in an attempt to rescue low frequency B-cell precursors. Supernatants from more than 4500 hybridomas surviving hypoxanthine-aminopterin-thymidine:ouabain selection were screened against human lung tumor cells in an enzyme-linked immunosorbent assay. Over 360 hybrids showed significant levels of activity, although most were not tumor cell specific since they also reacted with EBV-infected cells from the lymphocyte donor. Two hybridomas showed apparent specific binding early after fusion, but this activity was lost upon continued growth although, in general, hybrids continued to secrete high levels of immunoglobulin M (up to 50 micrograms/ml), in some cases, beyond 1 year in culture. The human EBV-hybridoma system described here may be useful for rescuing low-frequency tumor-reactive B-cell precursors in lung cancer patients.