Effects Of Donor Immatural Dendritic Cell On Acute Vascular Rejection

Objectives: To evaluate the effect of donor immatural dendritic cells on the acute vascular rejection by the model of heterotopic cardiac xenotransplantation from mouse to rats.Then,we explore the mechanisms of immuneotolerance of heart xenotransplantion.Methods: Dendritic cells from murine bone marrow were cultured with standard does or low dose of GM-CSF.Then identify DCs through following ways.Cells morphous characteristic were observed through the transmission electron microscope.The expression of surface molecules in DC,including CD11c, CD86, MHC-â…¡, was examined by flow cytometry. Capacities of stimulating xenogenic T cell proliferation were detected by performing mixed lymphocyte reaction.Donor(mouse) and recipient (SD rat) were divided randomly into three groups. Group A (Control group):without pretreatment; Group B (GM^hiDC group): 7 days before transplantation, the recipients were injected with GM^hiDC in vein; Group C (GM^loDC group): 7 days before transplantation, the recipients were injected with GM^loDC in vein. After different pretreatments to the recipients, the cervical heterotopic heart transplantation from mouse to rat were performed. 1 day before transplantation, CD4+CD25+ T regulatory cells, IL-10,TGF-β1 were detected in peripheral blood of rat. The survive time of xenograft was measured and the histopathologic observation was carried out after the graft arrest.Results:(1)The expression of CD11c of cells cultured with GM-CSF from murine bone marrow :standard does group : 71.94±2.92%,low dose group: 70.46±2.53%, The expression of CD11c of the two group is not significantly different (P >0.05).(2)The expression of MHCII,CD86 of CD11c+ cells(DCs): GM^hiDC: 66.47±2.55%, 11.43±1.87 %,GM^loDC: 59.92±3.50%, 0.98±0.56%. The expression of MHCâ…¡, CD86 of GM^hiDC is higher than that of GM^loDC (P<0.05).(3)The results of MLR: GM^hiDC(OD): 1.1±0.08, GM^loDC(OD): 0.60±0.03 ; GM^hiDC (effect of stimulator): 173.81±10.05%,GM^loDC(effect of stimulator): 49.03±5.54%, There was difference between GM^hiDC and GM^loDC (P<0.05).(4)MST(day): group A: 1.98±0.51, group B: 1.8±0.57. There is no difference between two groups (P>0.05). group C: 3.2±0.27, which is longer than group A and group B (P<0.05).(5)Pathology: All donor hearts showed acute vascular rejection(AVR). (6)The quantity of CD4+CD25+ T regulatory cells in peripheral blood of rat: group A: 2.7±0.57%, group B: 2.89±0.81%, group C: 5.54±1.18%. The quantity of group C is higher than group A and group B(P<0.05). (7)IL-10, TGF-β1 in peripheral blood of rat: group A: 18.87±2.69 pg/ml, 25.78±3.26 pg/ml, group B: 20.74±5.36 pg/ml, 27.07±5.24 pg/ml, group C: 26.12±4.88 pg/ml, 34.00±3.80 pg/ml. The level of group C is higher than group A and group B(P<0.05).Conclusions: Using of GM-CSF as stimulator in the murine bone marrow cell culture can obtain DCs with high quality and high purity.The population. DCs cultured with standard does of GM-CSF were a mixture of matural DCs and immatural DCs(CD11c+,MHCIIhi,CD86+).DCs cultured with low does of GM-CSF were phetotypically immatural DCs(CD11c+,MHCIIlow,CD86₎, and the capacity of inducing xenogeneic T cells proliferation is lower than GM^hiDC. Injecting with donor imDC in vein can suppress the AVR to a certain extent and also prolonged the MST, which may be related to the generation of CD4+CD25+ T regulatory cells in peripheral blood of recipients. CD4+CD25+ T regulatory cells induces immune tolerance through cell-contact denpendent mechanism and cytokines probably.