| Dendritic cells (DCs) are important functional antigen-presenting cells that play an essential role in initiating and modulating immune responses.The maturation and subtypes of DC determine the balance of immune activation and tolerance .Their mature states are crucial for the induction of T-cell-mediated immune reactions. "Tolerogenic DCs" stand for a new concept in the immunology of transplantation and immature DCs belong to this category.Characteristics of the low expressions of co-stimulatory molecules and the maintenance of T cell anergy have endowed immature DCs with important significance in immune tolerance. Hirano et al. have successfully induced permanent tolerance in an allograft model by intravenous injection of immature DCs. Therefore, the mechanism of T cell anergy related with DCs and research in applying immature DCs to establish donor-specific immune tolerance have become one of the new frontiers in the field of transplantation immunity.The CD47 Ag, an Ig superfamily transmembrane glycoprotein widely expressed in most cells and tissues(including DCs),has been found to be intimately related with the immune system and nervous system.Our data also showed the expressions of CD47 on immature and mature DCs were high ,which were about to 94%-98% level.The CD47 molecule has multiple modulations on the immune system with its ligands—integrins.SlRPs and TSPs.The CD47 ligands can serve to a"fine tune " the inflammatory response by regulating the rate of PMN and monocytes migration and inducing T cell.DCs and monocytes into apoptosis. Therefore synthesizing variable artifical ligands to mimic the effects of CD47 engagement to interfere with the immune response has become an new highlight to the immunologists.lt reported that the artifical mAb of CD47 molecule can make T cell anergy and inhibit the maturation of DCs.However ,none research relative to this subject has been proceeded in China. In this study, the soluble anti-CD47 mAb,B6H12, was selected as an ligand of CD47 molecule, whether any observed influence on DCs maturation and function,which retain DCs in "an relatively immature stage" ,could be ascribed to the effects of this CD47 ligation.Thus it may enrich the knowledge of the potential application of the engagement.In order to explore the influences of CD47 ligation on DCs maturation,function and cell signal transduction,we established a stable culture system of DCs in vitro firstly.The study aimed to enucleate the probable immune mechanisms of the integrin associated protein with its ligand and to find the latent signal transduction pathway related with the maturation of DCs.The results of the optical and transmission electron microscope revealed that the peripheral monocyte progenitors successfully developed into DCs with the combination of cytokine, GM-CSF, 1L-4 and lipopolysaccharide in our culture system of DCs. The immature DCs, appeared to have much relatively shorter processes on the surface and fewer organells in the cytoplasm compared with its counterpart — mature DCs,which turned to have even more abundant cytoplasmic extensions, more mitochondrias and less lysosomes,irregular large nuclei in the cytoplasm. DCs treated with anti-CD47 mAb showed a semblable outline with the immature DCs.The shorter dendrites and fewer organells distinguished them from the mature DCs and the control mAb treated DCs.Compared with the other two groups in which DCs were treated with or without the isotype control mAb, the expressions of CD80, CD86, CD83, CDla, HLA-DR in B6H12 mAb(10μg/ml)treated group decreased significantly via flow cytometry analysis.The differences were significant between groups, [CD80 (F=9.924, P<0.05) ,CD86 (F=l8.461, P<0.01 ) ,CD83(F=6.012, P<0.05),CDIa(F=58.021, P<0.01 ),HLA-DR(F=53.174, P<0.01 )], The phenotypes of DCs treated with or without B6H12 mAb were as follow: CD80~+(68.14±7.41)% vs(89.17± 8.59)%,CD86~+(67.33 + 4.71)% vs(87.27 + 3.56)%,CD83~+(40.08 + 14.80)% vs(72.77 ± 8.68)%,CDla~+(66.45±4.06)% vs (95.93 + 3.03) %, HLA-DR~+(40.67± 13.48)% vs(98.97± 1.01)%.Allo-MLR was... |
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