Aim: To explore the antitumor effects of dendritic cells (DCs) modified with different forms of hepatocellular cancer antigens.
Methods: DCs were modified with freeze-thawed H22 cell lysate, small molecular H22 peptides and Hsp70-H22 peptide complex, respectively. The cytotoxicity of DCs-activated CTLs to H22 cells was detected by MTT colorimetry. The expression level of IFN-gamma mRNA in splenocytes was detected by RT-PCR. The DCs modified with different antigens were used to immunize mice and then the suppressive effects on the growth of tumor were measured.
Results: The DCs modified with H22 peptides alone could not activate CTLs. The ability to activate CTLs by DCs modified with Hsp70-H22 peptide complex was stronger than that by DCs modified with freeze-thawed H22 lysate, with the killing rates of CTLs being 47.3% and 18.3%, respectively. The expression level of IFN-gamma mRNA in 3 groups of splenocytes was consistent with the killing rate of CTLs.The growth of H22 cells in mice immunized with DCs modified with freeze-thawed H22 lysate or Hsp70-H22 peptide complex was suppressed, but the suppressive effect of the latter was stronger than that of the former. The tumorigenesis rate in the Hsp70-22 peptide complex group was only 40%, whereas the tumorigenesis rates in the other two groups were 100%.
Conclusion: Hsp70-H22 peptide complex is a strong sensitizer for DCs, which participates in immune rejection of tumor through activating CTLs and inducing CD4 (+) T cells to differentiate into Th1 cells.