Direct intratumoral introduction of therapeutic or regulatory genes is a developing technology with potential application for cancer gene therapy.Macrophage inflammatory protein-I beta(MIP-Iβ)is a chemokine which can chemoattract immune cells such as T cells.In the present study,murine colorectal adenocarcinoma CT26 cells were transfected with a recombinant adenovirus (AdhMIP-Iβ)carrying the human MIP-Iβ gene.24 h post-transfection,hMIP-1β levels reached approximately 980 pg/ml in supernatants of 10~6 hMIP-Iβ-transfected CT26 cells.Moreover,the supernatants exhibited chemotactic activity for CD8^+ T cells,CD4^+ T cells,NK cells and immature DCs.Intratumoral injection of AdhMIP-Iβ significantly inhibited tumor growth and prolonged the survival time of tumor-bearing mice.Intratumoral hMIP-Iβ gene transfer also induced powerful tumor-specific CTL responses in vivo.The therapeutic effects of hMIP-Iβ gene therapy were greatly reduced following in vivo depletion of both CD4^+ and CD8^+ cells,but were unaffected by depletion of single T cell subsets.Immune cell depletion experiments also revealed that NK cells played an important role in hMIP-1β-induced antitumor responses.These results suggest that intratumoral expression of hMIP-1β has the potential effect to induce host antitumor immunity and may prove to be a useful form of cancer gene therapy. Cellular & Molecular Immunology.2004;1(3):199-204.
