Abstract: Objective To investigate the proliferation and cytotoxicity of cytotoxic T lymphocyte (CTL) induced by ovarian cancer cells transfected with a CD80 gene containing retroviral vector. Methods The ovarian cancer cell line TYK cells were transfected with retro-virus vector PLXSN-hCD80. After geneticin (G418) selection, the CD80 expression of the transfectants was confirmed by flow cytometry. CTL was induced by co-culture of CD80-expressing TYK cells (TYK-hCD80) and peripheral-blood mononuclear cells (PBMC) in the presence of anti-CD3 monoclonal antibody (McAb). Proliferation of PBMC was measured using 3?H-Thymidine incorporation assay. The lysis activity of CTL toward tumor cells was determined using methyl thiazolyl tetrazolium (MTT) assay. Results After transfection and G418 selection, the CD80 expression was proved by flow cytometry. The highest rate of CD80 expression was 84.9%. The TYK cell line expressing high CD80 was named TYK-hCD80. In the presence of anti-CD3 McAb,TYK-hCD80 significantly enhanced proliferation of PBMC than TYK cells (3H-Thymidine incorporation, (40 604±842) vs (8 000±594) cpm (P<0.05). The lysis activity of CTL activated by TYK-hCD80 was higher than that of TYK(P<0.05). Conclusions Ovarian cancer cells expressing CD80 can induce the production of CTLs which have high lysis activity and high proliferation rate in the presence of anti-CD3 McAb. This study may provide the experimental basis for immunogenic therapy of ovarian cancer.