Primarily Study On Immune Function Of Polypeptide C25P Which Derived From Core Region Of VMIP-Ⅱ

Objective:Polypeptide C25P which derived from core region of vMIP-II using bioinformative analyzing methods is a Chemokine receptor 5 (CCR5) specific antagonist. CCR5 is one of the important targets of anti-HIV drugs. It has anti-HIV/SIV potency through antagonizing the co-receptors, thus might be served as a leading agent to anti-HIV drug development. In order to study on immune function of polypeptide C25P and provide a theoretical basis for the clinical application, the thesis first research the effects of polypeptide C25P on activation, proliferation and cell-cycle of mouse peripheral T lymphocytes, and then observe effects of C25P on immune system of Kuming mouse in vivo, to primarily investigate the machanism of the immunosup-pressive effect of polypeptide C25P.Methods:1. Mouse peripheral T lymphocytes were treated with different concentrations of C25P, and stimulated with phytohemagglutinin(PHA). Fluorescence conjugated monoclonal antibodies and flow cytometry were used to detect the expression of CD69. The proliferation of T lymphocytes was analyzed by MTT assay. And the cell-cycle distribution was analyzed by propidium iodide(PI) staining.2. Kuming mouse were randomized into one negative group and three test groups continuously intra-peritoneal injection for 30 days, blood and lymphoid tissue samples were taken at various time points of animal treatments. Serum C25P antibodies were tested by ELISA. Peripheral blood mononeuclear cells(PBMCs) were prepared for total T cells (CD3+), CD4+and CD8+T cells calculation on FACS and determination of lymphocytes trans-formation ratio. IL-2,INF-γand IL-10 were tested by ELISA. Lymphoid tissues biopsy clippings were examined and cells apoptosis indexes were determined.Results:1. In a dose-dependent manner, polypeptide C25P (20,40,80μmol/L) can enhance T lymphocytes activation index (P＜0.05) stimulated by PHA, and enhance proliferation index (P＜0.05) stimulated by PHA, as well as the progression of T lymphocytes in S phase.2. Long-term administration of C25P didn't raise strong antibody response in Kuming mouse. Increasing CD3+, CD4+and CD8+T cell percentages in PBMCs (P＜0.05) with normal CD4+/CD8+ratio and lymphocytes transformation ratio (P<0.05) were observed during the C25P administration period. The expression of cytokines IL-2,INF-y and IL-10 were significantly increased(P<0.05). The thymus index and spleen index raised(P<0.05). No notable pathological change of various organs was seen and the apoptosis rates of lymphocytes were not obvious increased.Conclusion:1. Polypeptide C25P can enhance activation, proliferation and cell-cycle of mouse peripheral T lymphocytes, indicating that C25P could potentiate the function of T lymphocytes.2. The antigenicity of C25P in Kuming mouse is not significant, long-term C25P administration could stimulate the immune system by prompting T-cells functions. Thus, C25P has a measurable immunostimulatory effect, which provides valuable experimental evidence for further research.