Anti-tumor immunotherapy is an important form of adjuvant cancer treatment, with the potential to improve the prognosis[1–4]. It has been shown that tumor cell vaccines (TCVs) modified with the nano-sized hapten dinitrophenyl (DNP) are efficacious against malignant melanoma, both in animal studies and human trials[5, 6]. However, whether DNP-modified TCVs can also induce effective immune reactions against other types of malignancy has not been well evaluated. In this work, we investigated whether DNPmodified TCVs could enhance lymphocytes’ cytotoxicity against two types of human caner cells
, including the breast cancer cell line MCF7 and the lung cancer cell line H23. The results showed that both the unmodified and the DNPmodified TCVs produced significantly higher tumor inhibition rates in MCF7 and H23 cells compared to the cases without TCVs. In the MCF7 study, the DNP-modified TCVs also resulted in a significantly higher tumor inhibition rate than the unmodified TCVs. Moreover, DNP was compared with another TCV modification agent, the New Castle Disease Virus of Ulster Strain (NDV Ulster), and was found to have similar effects as the latter in enhancement of anti-tumor immune reaction. In addition, both the unmodified and the modified TCVs triggered significantly stronger inhibition of the tumor cells than the non-tumor cells, suggesting that the anti-tumor immune effects were relatively tumor-specific. These findings suggest that DNP-modification of TCVs may have prospective application in immunotherapies against multiple types of human cancer in addition to malignant melanoma.