Alteration and biological significance of peripheral dendritic cells in patients with chronic idiopathic thrombocytopenic purpura / 中华血液学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the quantity and function of circulating dendritic cells (DC) in patients with chronic idiopathic thrombocytopenic purpura (ITP).</p><p><b>METHODS</b>High dose dexamethasone (HD-DXM) at a dose of 40 mg orally per day for four consecutive days was the initial treatment for chronic ITP patients. Flow cytometry was used to analyze the number of myeloid DC (mDC), plasma cytoid DC (pDC) and CD4+FOXP3+ T cells in patients before and after the treatment, meanwhile the co-stimulatory molecules on circulating DCs were assayed as well. Monocyte-derived DCs and CD4+ T cells were co-cultured with autologous or allogeneic normal fresh platelets and after 6 days of incubation H-TdR was used to assay the proliferation of CD4+ T cells.</p><p><b>RESULTS</b>The absolute numbers of circulating mDC and pDC were not significantly different between pre-treatment patients and healthy controls (P > 0.05 and P >0.05). However, percentage of CD4+ FOXP3+ T cells was decreased (P < 0.01), and their percentage was inversely correlated with the number of pDC and mDC (r = -0.396, P =0.045 and r = -0.410, P =0.037). The initial response rate to HD-DXM was 92.3%. After 4-days treatment, CD4 FOXP3+ Treg cells increased (P <0.01) while pDCs decreased (P <0.01). Although mDCs increased after HD-DXM (P <0.05), their CD11c expression level was decreased (P < 0.01), the mean fluorescence intensity (MFI) decreased from 340 +/- 30 before treatment to 199 +/- 21 after treatment. The inverse correlation between pDCs and CD4+ FOXP3+ Treg cells remained (r= -0.524, P =0.006) while that between mDCs and Treg cells disappeared (r = - 0.360, P =0.071). The MFI of CD86 on DCs was higher in ITP patients than in healthy controls (P <0.05), while the proportions of CD86, CD40, CD80 and the MFI of CD40, CD80 in ITP patients were normal (P > 0.05). DCs from chronic ITP patients co-cultured with autologous or allogeneic platelets were highly efficient in stimulating autologous CD4+ T cells proliferaton as compared to those derived from healthy donors (P < 0.05 and P <0.05).</p><p><b>CONCLUSION</b>DCs may play a role in the pathogenesis of chronic ITP in relation with CD4+CD25+ Treg cells.</p>