The critical role of Th1-dominant immunity in tumor immunology

To investigate the precise role of antigen-specific Th1 and Th2. cells in t umor immunity, we developed a novel adoptive tumor-immunotherapy model usin g OVA-specific Th1 and Th2 cells and an OVA gene-transfected tumor. This th erapeutic model demonstrated that both antigen-specific Th1 and Th2 cells h ad strong antitumor activity in vivo with distinct mechanisms. However, imm unological memory suitable for the generation of tumor-specific cytotoxic T lymphocytes was induced only when tumor-bearing mice received Th1 cell the rapy, but not Th2 cell therapy. Thus it was strongly suggested that Th1-dom inant immunity is critically important for the induction of antitumor cellu lar immunity in vivo. We also proposed that several immunomodulating protoc ols using interleukin (IL)-12, IL-12 gene, the natural killer T cell ligand alpha-galactosylceramide, or Th1 cytokine-conditioned dendritic cells migh t be useful strategies for the induction of Th1-dominant immunity essential for the development of tumor-specific immunotherapy.