树突细胞及其Toll样受体4在特发性血小板减少性紫癜发病中的作用

目的 研究特发性血小板减少性紫癜(ITP)患者树突细胞(DC)免疫表型及其Toll样受体4(TLR4)的表达,探讨其在ITP发病机制中的作用.方法 取ITP完全缓解患者及未达完全缓解患者治疗前后及正常人外周血,分离单个核细胞,加入细胞因子rhGM-CSF及rhIL-4诱导DC,用流式细胞术检测DC表型;酶联免疫吸附法检测DC培养上清液中IL-12p70.应用RT-PCR检测DC的TLR4表达.结果 21例ITP完全缓解患者治疗前DC的CD80和CD86阳性表达率分别为(51.60±13.47)%和(61.50±15.93)%,15例未达完全缓解者CD80和CD86分别为(53.29±19.49)%和(62.91±18.43)%,均高于正常对照的(36.03±15.43)%和(40.28±11.49)%(P＜0.01).治疗后ITP缓解患者组CD80和CD86表达率分别降为(36.48±15.19)%和(44.05±17.70)%,与治疗前比较差异有统计学意义(P＜0.01),与对照组相比差异无统计学意义(P＞0.05);未完全缓解组CD80和CD86分别降为(52.30±20.98)%和(49.79±20.28)%,但与治疗前相比差异均无统计学意义(P＞0.05),CD80仍高于正常对照组(P＜0.05),而CD86与对照组比较差异亦无统计学意义(P＞0.05).地塞米松(DXM)治疗缓解组患者治疗前DC培养上清IL-12p70为(67.52±14.43)pg/ml,明显高于正常对照的(39.78±10.03)pg/ml(P＜0.01),治疗后IL-12 p70的表达降至(43.90±8.49)pg/ml,与治疗前比较差异有统计学意义(P＜0.01),与正常对照组相比无明显差异;而未缓解组患者DC培养上清IL-12p70则由治疗前的(65.35±12.52)pg/ml降至(48.45±9.68)pg/ml(P＜0.01),但仍高于正常对照(P＜0.05).治疗缓解组ITP患者DC的TLR4 mRNA相对表达水平为0.69±0.17,明显高于正常对照组的0.31±0.09(P＜0.01),治疗后ITP患者DC的TLR4 mRNA相对表达水平降为0.35±0.11(P＜0.01),与正常对照组相比无明显差别;未缓解组DC的TLR4 mRNA相对表达水平由治疗前的0.65±0.09降至治疗后的0.52±0.21(P＜0.01),但后者仍高于正常对照组(P＜0.01).结论 DC可能通过其Toll样受体及细胞因子的分泌在ITP发病中起重要作用.

Role of dendritic cells and their Toll-like receptor 4 in the pathogenesis of idiopathic thrombocytopenic purpura

Objective To study the surface antigen of the dendritic cells(DC) and their Toll-like receptor 4 (TL,R4) expression in patients with idiopathic thrombocytopenic purpura( ITP), and to explore their role in ITP pathogenesis. Methods The peripheral blood mononuclear cells isolated from complete remission patients (CR), non- complete remission patients (n-CR) and normal controls were stimulated by rhGM-CSF and rhlL-4. The surface antigen of the DC was analyzed by flow cytometry. The level of IL-12p70 in the supernatant was detected by enzyme linked immunosorbent assay. The expression of TLR4 mRNA of DC was detected by real time PCR. Results In the 21 CR ITP patients, the expression of both CD80 and CD86 in DC was significantly increased compared with that in normal controls [(51.60 ± 13.47)% vs (36. 03 ±15.43)%, (61.50 ± 15.93)% vs (40.28 ± 11.49)%, respectively] (P＜0.01). The expression of CD80and CD86 in n-CR group was also significantly increased [(53.29 ± 19.49)% and (62.91 ± 18.43)%, respectively] (P ＜ 0.01 ). After HD-DXM treatment, both CD80 and CD86 in CR patients were decreased (P＜0.01). There was no difference between the DXM treatment patients and the normal controls. In n-CR group, there was no difference in CD80 and CD86 expression before and after DXM therapy [( 52.30 ±20.98% and (49.79 ±20.28)%, respectively] (P＞0.05). CD80 was still higher than normal(P ＜0.05),while CD86 was not changed. The level of IL-12p70 in CR ITP patients before treatment was significantly higher [(67.52 ± 14.43 ) pg/ml] than that of the controls [(39.78 ± 10.03 ) pg/ml] ( P ＜ 0.01 ), and after treatment, was significantly decreased to (43.90 ±8.49) pg/ml, being no difference from that in control. In n-CR group, IL-12p70 was lower after treatment [( 48.45 ± 9.68 ) pg/ml] than that before treatment [(65.35 ±12.52) pg/ml] (P＜0.01), but still higher than that in control(P ＜0.05). The TLR4 mRNA level in DCs of CR ITP patients before treatment were significantly higher 0.69 ±0.17 than that of controls (0.31 ± 0.09 ) ( P ＜ 0. 01 ) and after treatment, was reduced to 0. 35 ± 0. 11, being no difference from that in control. In n-CR group, TLR4 mRNA was decreased from 0. 65 ± 0. 09 to 0.52 ± 0.21 after treatment ( P ＜0.01 ), but still higher than normal( P ＜0.01 ). Conclusion DC may play an important role in ITP by their Toll-like receptor and cytokine secretion.