Tumor Rejection Effects of Allorestricted Tumor Peptide-Specific CD4+ T Cells on Human Cervical Cancer Cell Xenograft in Nude Mice

Abstract

Generation of tumor specific alloreactive CD4+ T cells is important to circumvent tumor tolerance. Here, we generate allorestricted peptide-specific CD4+ T cells by coculture of lymphocytes and autologous monocytes bearing allogeneic HLA-DR15 molecule associated with its restricted peptide. Binding of a dimeric HLA-DR15/IgG1-Fc fusion protein (the dimer) to HLA-DR15 negative (HLA-DR15-ve) monocytes made the monocytes coated with the allogeneic epitope. An increased proliferation of CD4+ T cells and induction of Th1 cells appeared after coculturing of HLA-DR15-ve lymphocytes and the autologous monocytes loaded with the dimer. The cocultural bulks showed an increased frequency of the specific dimer-stained CD4+ T cells and the expanded CD4+ T cells exhibited an elevated IFN-γ production in response to specific TCR ligand. Tumor rejection effects of the allorestricted E7-specific CD4+ T cells raised by the coculture were observed in nude mice challenged with human cervical cancer cell SiHa expressing both HLA-DR15 and E7 antigens, as the tumor avoidance and life span of the mice were improved after adoptive transfer of the CD4+ T cells. This study may help to develop strategies to separate graft-versus-leukemia or graft-versus-tumor reaction from graft-versus-host disease, and add to the pool of human high-avidity TCRs specific for tumor or virus antigens.