Clinical And Basic Research Of Thrombotic Thrombocytopenic Purpura

Part I Clinical analysis of 106 patients with acquired Thrombotic Thrombocytopenic PurpuraObject:Thrombotic Thrombocytopenic Purpura(TTP) is a life-threatening disease characterized by systemic microvascular thrombosis caused by adhesion of platelets to ultra-large VWF(UL-VWF) multimers. These multimers accumulate because of a deficiency of the processing enzyme ADAMTS13. Plasma exchange(PE) is the basic and best treatment in treating TTP nowadays. Comprehension analysis 106 patients of acquired TTP(a TTP) with clinical characteristics, treatment strategies and treatment outcomes, help to learn about the level of clinical diagnoses and treatment of TTP in China.Methods:We have retrospectively analyzed the clinical data, laboratory test results, treatment strategies and outcomes of the 106 a TTP patients who confirmed and registered in our center from 2007 to 2015. We also telephoned them to learn more about the relapse rate. Relevant statistical analysis were performed using SPSS17.0 and Graphpad.Results:The median age of the 106 patients is 40.5 years, ranging from 13 years to 90 years. The proportion of men and women is 1:2.21. There were 20 patients(18.9 percent) have the typical pentalogy of TTP at the diagnosis of TTP. The median number of plasma exchange is 7 times(range from 1 to 30). The death rate in our group is 23.6 percent and the relapse rate is 19.8 percent. There were significant differences between death group and survival group in age and creatinine(P﹤0.05); but no significant differences in relapsed group and non-relapsed group. Twenty-nine patients had received Rituximab in addition to plasma exchange. Seventy patients had given plasma exchange treatment. The other seven patients did not received plasma exchange treatment. The mortality rate and relapsed rate in the Rituximab group were significantly decreases(0% vs 22.9%,3.4% vs 24.3%). But there were no significant difference in plasma exchange numbers, the days of platelet and ADAMTS13 recovery. Four patients were given the Rituximab at the doses of 100mg/day for 4 times in the remission phase and with no relapse.Conclusion:In recent years, the number of confirmed cases of thrombotic thrombocytopenic purpura increased significantly. Have disease vary, but significant thrombocytopenia and microangiopathy hemolytic anemia is still the fundamental to the diagnosis of TTP and plasma ADAMTS13 activity and inhibition test is important auxiliary value for disease diagnosis. Timely and full of plasma exchange(PEX) is the key to the treatment of a TTP, a few patients after more than ten times of PEX to observe signs of improvement, and thus stop PEX should not be too early. Combined with Rituximab can obviously reduce the recurrence rate and mortality, but the use of time, there are still different opinions, such as dosage, course of remains to be seen. Part II The vitro experimental study of N-Acetylcysteine in the treatment of Thrombotic thrombocytopenic purpuraObjective:Plasma exchange and Rituximab can dramatically decreased the mortality and recurrence rate of thrombotic thrombocytopenic purpura. But some patients were refractory to these treatment. We discuss the effects of N-Acetylcysteine(NAC) on the UL-VWF and the platelets functions depend on the VWF and aim to provide the theoretical basis for the use of NAC in the treatment of TTP in clinical.Methods:Mixing the citrate anti-coagulation normal peripheral blood platelet rich plasma with different concentrations of NAC(the final concentration was 1mmol/L; 1.5mmol/L; 2mmol/L; 3.2mmol/L; 6.4mmol/L). Incubation in the temperature of 37 centigrade for half an hour and then detect the platelet function(Rist:1.25mg/ml); 2. Mixing the citrate anti-coagulation normal blood plasma with different concentrations of NAC(the final concentration were 0.25mmol/L; 0.375mmol/L;0.5mmol/L; 1mmol/L; 1.5mmol/L;2mmol/L;3.2mmol/L;6.4mmol/L). Incubation in the temperature of 37 centigrade for half an hour and then add in NEM to terminal the function of NAC. VWF polymer analysis was applied by 1.3% agarose electrophoresis. We repeated the experiment twice in order to verify the result.Results:1. The platelet function can be suppressed by NAC. The inhibitory rates are 2.06±0.76%;2.87±2.66%;4.84±3.82%;38.01±26.19%;68.34±11.77% separately in different density of NAC; 2. UL-VWF can be degraded by NAC. We can see large and medium-sized molecular fragments decreased significantly when the density of NAC≥1mmol/L.