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Introduction of the interleukin-4 (IL-4) gene into cells derived from human tumor tissue provides a means for generating a specific tumor vaccine. Such a vaccine could be produced by either transducing tumor-derived stromal cells with the IL-4 vector and coinjecting tumor cells, or by transducing the tumor cells themselves. We have developed a protocol for culturing cells from non-small cell lung tumors and routinely produce tumor cultures from 25% of tumors, and stromal cultures from >80% of specimens. Several of these cultures were transduced with the incompetent retroviral vector G1NaSvi4.25, which encodes the human IL-4 cDNA and the G418-resistance gene. Infection of cells by viral titers of 2-5 x 104 plaque-forming units/ml, and a multiplicity of infection of 0.1:1 to 1:1 yielded transfer efficiencies of 3.3-32.0 transfectants per 104 cells in six of eight attempts. Following selection with the neomycin analog G418, IL-4-producing cells were isolated. IL-4 titers ranged from 142 to 593 U/ml/106 in a 24-h collection. Successful transfer of the IL-4 gene was demonstrated by polymerase chain reaction amplification of cDNA derived from reverse-transcribed total RNA, by immunohistochemistry, and by enzyme- linked immunosorbent assay. The IL-4-producing cells were shown to stimulate the proliferation of autologous peripheral blood lymphocytes in one individual by 7.5-fold over control and by 4.1-fold over non-IL-4 producing tumor cells. Gene transfer was performed between 18 and 60 days after acquisition for stromal cells and within 150 days for tumor cells. Cells from lung cancer patients may have potential for generating tumor vaccines. In addition, use of lung tumor-derived stromal cells for transfection may have some advantages over dermal fibroblasts for use in gene therapy.