Immature Dendritic Cells Generated With Low Doses Of GM-CSF From Mouse Bone Marrow Are Maturation Resistant

In the treatment of full-thickness large body burns, it is the most important that how to cover the wound early and effectivly, which has not been solved yet. Allogeneic skin transplantation is a good idea, but the rejection after transplantation limits its application. The study is based on the recent achievements of organ transplantation -combined transplantation with the same donor drived skin graft and immature dendritic cells can induce tolerance successfully. We obtained third-party immature DC which carry skin donor drived MHC in cell surface by microchromosome, and assessed the effect of induction of transplantation tolerance on mixed lymphocyte reaction, animal test and clinical test.The study can settle the inconsistence of the origin of skin graft and immature DC which often happens in clinic, and make a breakthrough in histocompatibility, which is also donor specific and convenient.A method to generate immature DC from mouse bone marrow is the first step of the study,which contribute to further skin transplantation.Dendritic cells are the most important professional antigen presenting cells,which induce strong immune reaction and play an essential role in infection,transplantation rejection,tumor immunity. But immature dendritic cells, which are absent of costimulating molecules,can not only activate T cells but also induce T cells anergy. As a result, they can lead to antigen specific immune tolerance. It is difficult to obtain immature dendritic cells from tissues directly, as they spreads all over the body and the amount is so low. The conventional methods to get immature dendritic cells are to culture stem cells with some kinds of cytokines, which are different in sorts and dosages of cytokines, time, culture medium, and influence the effect of the induction of tolerance.In this study, dendritic cells were cultured from mouse bone marrow progenitors in low concentrations of GM-CSF (GMlow DC) or high concentrations of GM-CSF (GMhigh DC). We identified these cells on morphology, phenotype and functional properties. And we hope the immature dendritic cells can keep the immature character when they are applied in burn patients, who have plenty of LPS. So we assessed the effect of LPS,TNF-α,IFN-γ on maturation of these immature DC in vitro.The study was divided into two parts:Ⅰ. Generation of immature dendritic cells frommouse bone marrow. Ⅱ. Maturation resistant of immature dendritic cells.The major results and the conclusion were as follows: 1. GMlow DC had typical characters of DC and were phenotypically immature, weak stimulators of allogeneic and peptide-specific T cell responses. The results suggested the method was feasible.2. The concentrations of rm GM-CSF were correlative with maturation degrees of DC. Generally speaking, immature DC were yielded in low concentrations of GM-CSF, whereas mature DC were generated in high concentrations of GM-CSF.3. Immature DC were resistant to maturation by LPS, TNF-α,IFN-γ, and stimulatory activity in MLR was not enhanced.