Cytotoxic T lymphocytes (CTL) against human lung cancer cells are difficult to induce by a conventional method using tumor cell stimulation probably due to an insufficiency of tumor antigens (TA) or costimulatory molecules such as CD80. We, therefore, investigated the potential of CD80-transfected tumor cells as stimulators of the in vitro induction of autologous tumor-specific CTL from regional lymph node lymphocytes in patients with lung cancer. Five non-small cell lung cancer cell lines (two adenocarcinomas, 1 squamous cell carcinoma, 1 large cell carcinoma and 1 adenosquamous cell carcinoma) were established from surgical specimens and were successfully transduced with a plasmid constructed with expression vector pBj and human CD80 cDNA, using a lipofection method. CD80-transfected tumor cells (CD80-AT) significantly augmented the proliferation of autologous lymphocytes from all cases as compared with non-transfected tumor cells (AT). AT-stimulated lymphocytes from 4 out of 5 cases did not show any cytotoxicity against AT;however, lymphocytes stimulated with CD80-AT exhibited substantial cytotoxicity against parental AT in all 5 cases tested. AT-stimulated lymphocytes derived from only one out of 5 cases showed major histocompatibility complex (MHC)-class I-restricted cytokine production in response to AT, while the MHC-class I-restricted responses were found in CD80-AT-stimulated lymphocytes from 4 out of 5 cases. These results indicate that CD80 on tumor cells could be a beneficial costimulatory molecule to elicit CTL against lung cancer, and also show that TA recognized by CTL was frequently expressed on lung cancer cells.

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Tumor-infiltrating lymphocytes consist predominantly of T cells, whereas B cells, plasma cells, and natural killer cells are observed with different degrees of frequency. We investigated the nature of tumor-infiltrating B lymphocytes (TIB) in human lung cancer. First, to examine the ability of immunogloblin production by TIB, cancer tissues were subcutaneously transplanted in severe combined immunodeficient mice, and the murine serum was examined for the concentration of human immunogloblin. Human IgG (huIgG) was detected in the serum of all 12 mice engrafted with lung cancer tissues. huIgM was almost undetectable. The levels of huIgG reached a peak approximately 6 weeks after engraftment and gradually decreased but were detectable until 20 weeks postengrafment. Serum from a large cell carcinoma-engrafted mouse reacted with a protein of 60 kDa derived from lung cancer cell lines (PC-9, Sq-1) and autologous tumor cells but did not react with cell lysates of normal lung tissue. Serum from an adenocarcinoma-engrafted mouse reacted with two proteins, 33 and 55 kDa, derived from lung cancer cell lines (PC-9, Sq-1, A549) and autologous tumor cells but did not react with the lysate of normal lung tissues. These results suggest that B cells infiltrating lung cancer tissues produce IgG that recognizes common tumor-specific antigen.

The AM have anti-tumor cytotoxicity in lung cancer although the cytolytic potential is heterogeneous and that the tumor lysis by AM is mediated by both TNF-alpha and NO production.

These results suggested the MAGE-3 peptide could be a potential target of specific immunotherapy for HLA-A2 patients with lung cancer.