| Dendritic cells (DCs), the most potent professional antigen presenting cells (APC), are efficient in phagocytosing, processing and presenting antigens to naive T cells, stimulating the proliferation and activation of naive T cells, and play a central role in initiating, regulating and sustaining immune responses.DCs reside in unperturbed tissues in an immature form, where they are adapted for capturing and accumulating Ags. Indeed, DCs possess a wide spectrum of recognition systems for an efficient screening of the tissue environment. A variety of danger signals, including microorganisms, dying cells, or proinflammatory cytokines, induce the terminal differentiation, also known as maturation, of DCs. DCs undergo a complex and exquisite differentiation and maturation procedure. Mature DCs migrate to lymph nodes, acquire potent Ag presenting capacity, and stimulate T cell responses vigorously. Moreover, maturation of DCs is strengthened during interactions with T cells by signals such CD40 ligand (CD40L) provided by T cells themselves. Mature DCs express high levels of Ag presenting and costimulatory molecules, and release large amounts of IL-12, thereby stimulating preferentially Thl responses. Thus, DC maturation is a key checkpoint in the initiation of immunity and has important consequences also on the quality of the immune response.Recently, applications of DCs in tumor, transplantation, and anti-infection immunology have been paid more and more attention. Therefore, investigation of the associated influential factors and mechanisms contributed to the development of DCs based vaccination protocols. Our research were divided into three sections as the foliowings:In the first section our research focused on expressions and interactions of costimulatory molecules and chemokine receptors during the procedure of the human peripheral blood monocytes derived dendritic cells (MDDC) differentiation and maturation, comparison the different biological effects between CD40 and TNF-stimulated MDDC, and investigation the roles of IL-2 and IL-2R complex in MDDC's activation and functions. The second section was about in vitro generation and activation of tumor specific CTL by CD40 or TNF-a stimulated MDDC combining a cocktail of cytokines. Costimulatory signals' effects on tumor specific CTL and the associated mechanisms were also investigated. Moreover, chemoattraction and migration ability, cytotoxic activity against tumor cells were assayed in vitro. The third section focused on study of the repressive effects of IL- 10 on the differentiation, maturation and biological functions of MDDC in vitro. These studies all contributed to the development of immunotherapy on malignant tumor in clinic.Part I : Expression of costimulatory molecules and chemokine receptors in dendritic cells and the related biological effectsObjective: Our study aimed to compare the different biological effects between CD40and TNF-a stimulated MDDC, including expressions of costimulatory molecules and chemokine receptors during the procedure of the human peripheral blood MDDC differentiation and maturation; investigate the roles of costimulatory signals and IL-2 in activation of tumor specific DCs and the associated mechanisms.Methods: DCs ultrastructures were observed by transmission electron microscopy; Expressions of costimulatory molecules and chemokine receptors of MDDC were analyzed by FCM. PD-L1, PD-L2, 4- 1BB and 4-1BBL mRNA transcription were detected by RT-PCR and Real-time PCR. Concentrations of IL-2, IL-10 and IL-12 in supernatant ofDCs were determined by ELISA. The ability of DCs chemoattracting T lymphocytes was measured by transwell assay. Expression of IL-2Ry chain were detected by western-blotting.Results: During the process of maturation, both of CD40mAb (5C11) or TNF-stimulated MDDC up-regulated expressions of CD40, CD80, CD86, HLA-DR, GL50, PD-L1 and PD-L2 (P>0.05); 4-1 BB and 4-1BBL were co-expressed in Ag loaded MDDC; Expressions of CD25 and CD83 were higher in CD40 activated MDDC than TNF-a stimulated MDD...
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