CD80 expression in an HLA-A2-positive human non-small cell lung cancer cell line enhances tumor-specific cytotoxicity of HLA-A2-positive T cells derived from a normal donor and a patient with non-small cell lung cancer

To generate non-small cell lung cancer (NSCLC)-reactive lymphocytes, we transfected an HLA-A2-expressing human NSCLC line (1355) with the cDNA encoding the lymphocyte co-stimulatory molecule CD80. Following selection in G418, 1355.7 demonstrated stable cell-surface expression of CD80. Allogeneic mixed lymphocyte tumor cell cultures (MLTCs) were established in 600 IU/ml IL-2 using HLA-A2⁺ normal donor peripheral blood mononuclear cells (PBMCs) stimulated with 1355-P (parental), 1355.7 or IL-2 alone. In 7 of 9 MLTCs, those stimulated with 1355.7 demonstrated enhanced growth after 30 to 45 days of culture. The predominant lymphocyte to grow in all MLTCs was a CD3⁺αβ⁺CD4⁺ T cell. In one case, lymphocytes stimulated with 1355.7 (MLTC 2389.7) exhibited preferential lysis of 1355. MLTC 2389.7 was cloned by limiting dilution, and 2 resultant cloids were shown to be NSCLC-reactive and dependent on both MHC class I and CD3 in their recognition of tumor cells. Additionally, allogeneic MLTCs were established using three HLA-A2⁺ NSCLC patients' PBMC. The predominant lymphocyte to grow in these MLTCs was a CD3⁺αβ⁺CD8⁺ T cell. In cytotoxicity studies, MLTC-UKY25.7 demonstrated preferential lysis of 1355-P, 1355.7 and an HLA-A2⁺ NSCLC cell line, 1650. Lymphocytes from this MLTC did not lyse K562, Daudi or an HLA-A2^- NSCLC cell line, 647. Our data suggest that CD80-expressing NSCLC tumor cells may enhance the generation of specific CTLs in vitro. These CTLs could be important reagents for use in cellular immunotherapy and/or in isolating tumor antigens for potential tumor vaccine development.