| Objective:Primary immune thrombocytopenia(ITP) is refractory, and is of high recurrence rate. As a new treatment, rituximab show a good effect.This study is to explore the change of surface antigen and function of rituximab on dendritic cells derived from patients with primary immune thrombocytopenia, and to explore the effective mechanism of immunotherapy.Methods:The peripheral blood mononuelear cells(PMNC) were isolated from remission patients with primary immune thrombocytopenia befoe and after low-dose rituximab infusion with Ficoll density gradient centrifugation method. The PMNC were stimulated for five days by rhGM-CSF and rhlL-4 in 5% CO2 air at 37℃incubator.Then all of DCs were culture with TNF-αfor 48 hours. The morphology of DCs was observed under inverted microscope everyday. On the seventh day, the surface antigen of the DCs were analysed by flow cytometry, meanwhile the levels of IL-12 p70 and TGF-β1 in supernatant were detected by ELISA.Results:①On the seventh day, rituximab-treated-DCs, compared with untreated -DCs didn't showed obvious tree-like protruding under inverted microscope.The cells were small and most of nucleus were centric.②Rituximab-treated-DCs compared with untreated -DCs,the expressions of CD80,CD83 and CD86 in dendritic cells were significantly lower [(36.41±2.82)%, (30.45±4.61)% and (41.98±4.17)% vs (55.14±7.30)%, (80.91±7.09)% and (59.03±3.43)% respectively,p<0.05].③The concentration of IL-12p70 [(50.17±14.52)pg·ml-1] was significantly lower than the untreated-DCs [(66.87±4.29)pg·ml-1],and the concentration of TGF-β1 [(9.7±0.31)ng·ml-1] is higher than the untreated-DCs [(2.7±0.36)ng·ml-1] (p<0.05).Conclusion:After the low-dose rituximab infusion, the surface antigen of ITP-DCs and the concentration of IL-12p70 reduced.While the concentration of TGF-β1 increased. Rituximab may achieve its therapeutic effect on ITP by downregulating the immunoreactivity of dendritic cells.
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