ABSTRACT
Objective: To study the anti-tumor immune effects of WT1 peptide vaccine in SCID mice with xenografted human monocytic leukemia. Methods: Twenty-four hours after intraperitoneal injection of human peripheral blood lymphocytes, the xenograft human monocytic leukemia model in SCID mice was established by subcutaneous inoculation of THP1 cells. The mice were randomly divided into three groups with eight mice in each. Blank control group was vaccinated with incomplete Freund's adjuvant (IAF). Helper T cell epitope group was vaccinated with helper T cell epitopes and IAF. WT1 group was vaccinated with WT1 peptide, helper T cell epitopes and IAF. When the tumor volume grew to 100 mm3, intraperitoneal injection of vaccine components started. The SCID mice were killed 14 days after vaccination. LDH release method was adopted to detect the specific CTL killing activity of spleen cells. Histological characteristics of tumor tissue were observed under microscope after HE staining. Flow cytometry was used to test the levels of peripheral blood CD3+/CD4+T cells, CD3+/CD8+T cells and CD4+CD25+ Treg cells. ELISA method was applied to detect the levels of serum immunoglobulin, IL-2, γ-interferon, TGF-β and IL-10. Results: The xenograft human monocytic leukemia model was successfully established in SCID mice and tumor developed in all the SCID mice. In WT1 group, the activity of mouse spleen cells on THP1 cells was significantly higher than that in helper T cell epitope group and control group (P<0.05). The mean weight and volume of tumor were significantly lower in WT1 group than in helper T cell epitope group and control group (P<0.05). A large amount of tumor cell degeneration and necrosis was observed under the microscope in WT1 group mice and few tumor cells survived. Peripheral blood levels of CD3+/CD4+T cells, CD3+/CD8+T cells, IgG, IFN-γ and IL-2 were all higher in WT1 group than in helper T cell epitope group and control group (P<0.05). However, peripheral blood levels of CD4+/CD25+Treg cells, TGF-β and IL-10 were all lower in WT1 group than in helper T cell epitope group and control group (P<0.05). Conclusion: WT1 polypeptide vaccine can effectively produce anti-tumor immunity and kill leukemia cells in SCID mice with exnografted human monocytic leukemia.
ABSTRACT
Background and purpose:Cytotoxic T lymphocyte (CTL) plays a vital role in the process of anti-tumor immunology. The aim of this study was to investigate whether changes in concentration of IL-2 (50, 200 and 1 000 U/mL) would affect the sub-population and cytotoxic function of cells cultivated by peptide-specific CTL induction systemin vitro and also observe whether using the concentration of IL-2 at a range of 50-1 000 U/mL isbeneifcial to regulatory cells (Tregs) enrichment.Methods:Peripheral blood from 10 healthy donors and 10 cancer patients that were HLA-A2 positive, were collected in the study. HLA-A2 restricted CTL epitope P321 (ILIGETIKI) derived from COX-2 pulsed with different concentrations of IL-2 were used to induce peptides-speciifc CTLin vitro. Flow cytometry was performed to analyze the proliferative capability, the proportion of different T-cell subsets, and secretion of perforin, granzyme B and IFN-γ. IFN-γ secretion was assessed by ELISpot assay.Results:High concentration of IL-2 increased the proliferative activity. The percentage of CD4+ T cells of cancer patient group was signiifcantly higher than that of healthy donor group, while the percentage of CD8+ T cells of cancer patient group was signiifcantly lower than that of healthy donor group. And there was no signiifcant difference in the percentages of CD4+ T cells, CD8+ T cells and Tregs among groups with different IL-2 concentrations. No difference was seen in cytokine (perforin, granzyme B, IFN-γ) secretion capacity of CD8+ T cells. ELISpot study revealed that high-dose IL-2 resulted in the increasing of IFN-γ secretion.Conclusion:The sub-population and the function of cells cultured by peptide-speciifc CTL induction systemin vitro are not affected by different concentrations of IL-2. Furthermore, high concentrations of IL-2 (50-1 000 U/mL) do not provide the enrichment for Tregs. Higher concentration of IL-2 is likely to cause high secretion of IFN-γ in ELISpot assay. In order to exclude the distraction of NK cells or NKT cells, the concentration of 50 U/mL is better choice.