[Soluble PD-1 can augment anti-tumor immunity induced by HSP70-peptide complex in tumor-bearing mice]. 
To explore the effect of soluble PD-1 (sPD-1) on the anti-tumor immunity induced by HSP70-peptide.  BALB/c mice were immunized with HSP70-peptide, then the cytotoxic activity of splenocytes was detected by MTT colorimetry.  Expression of PD-1 and its ligand on splenocytes was determined by semi-quantitative RT-PCR.  For some mice, sPD-1 plasmid was injected alone or in combination with HSP70-peptide and then the tumor weight and cytotoxic activity of splenocytes were measured.  sPD-1 alone had anti-tumor effect.  HSP70-peptide complex not only induced tumor-specific cytotoxic T lymphocytes(CTLs), but also promoted expression of PD-1 and its ligand.  The combination of sPD-1 with HSP70-peptide complex induced much more stronger anti-tumor effect as compared with sPD-1 or HSP70-peptide alone.  sPD-1 transfection in mice could enhance the cytotoxic activity of splenocytes from immunized mice.  sPD-1 enhanced the anti-tumor efficacy of HSP70-peptide.