| Chemokines play important roles in leukocyte traffic, inflammation, hematopoiesis, angiogenesis and oneogenesis. Chemokines are produced by an array of stromal cell types, including endothelial cells, macrophages, fibroblasts, and denclritic cells (DCs). Up to now, several chemokines have been found to be constitutively expressed in immature DC and mature DC. Besides chemokines, DCs have been shown to express lymphocyte-stiniulatory and hematopoietic-stimulatory cytokines. These data suggest DC could regulate immunity, hematopoiesis and angiogenesis through the production of chemokines and cytokines. Recently, we cloned and characterized a novel CXC chemokine from our human DC cDNA library, the full-length cDNA of which contains an open reading frame encoding 111 amino acids with a putative signal peptide of 34 amino acids. This CXC chemokine shares greatest homology with macrophage inflammatory protein (MLP)-2 a I P, hence was designated as MIP-2y. IvflP-2y is a potent chemoattractant for neutrophils and DCs. To further investigate the biological functions of MIP-2T, we expressed and purified the recombinant human MIP-2 Y in E. ccli. In large scale, then we conducted the Part I research: the physiological regulation effects of MIP-2T On hematopoiesis and immunity. And based on the results of Part I that MLP-2y can attract DC and activated T cell, promote I cell proliferation and activation, we conducted the Part II research: the antitumor effects and its mechanisms of MIP-2y. Abstract of Thesis for Doctor抯 Degree Xiang YS ~Th? Biological Functions of MIP-Zy Part I. Regulation of Hematopoiesis and Immunity by a Novel Human CXC Chemoldne M[P-27 1. Chemotatic activity. The results of chemotaxis assay using the Boyden chamber or endothelial cell-free Transwell demonstrated that MIP-2-y was a potent chemoattractant to immature DC (CD34~ cells-derived immature DC梔7, CD 1lc~ CDS3IOWCDS6IOW), but weakly or not to mature DC(CDIIC~ CD83~ CD86~ DC梔l 1, and LPS stimulated DC-dl 1). Except for SDF-l, MIP-2y was another CXC chemokine which can attract CD34~ IIPC in a dose-dependent manner. MIP-27can attract PHA-activated T cells (both CD4~ T and CD8~ T cells), but not attract freshly isolated I cells and B cells in vitro. 2. 1 cell activation. Our data showed that MIP-2y had a co-stimulating ability to promote T cell proliferation and enhance the secretion of Thl cytokines IL-2 and IFN-y, but had little or no effect on secretion of Th2 cytokines IL-4 and IL-b induced by si~b-opdmal dose of PHA. 3. Inhibition of DC function. MIP-2y inhibited DC to secrete IL-12 induced by CpG- ODNs, but increased DC to produce nitric oxide as detected by Griess?reagents assay. The FACS results showed that MIP-2y?down-regulated the expression of MI{C class TI molecules (I-A? and co-stimulatory molecules (CD4O and CD86) on DC. The DC抯 capacity of antigen presentation function (DC-T MLR) was also impaired after pretreated with MIP-27 in vitro. Besides, M[P-2y could selectively down-regulate the number and function of DC in spleen.The inhibitory effects of MIP-2y od DC may be a loop of self-feedback negative regulation. 4. Regulation of hematopoies...
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