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We report a 23 years old female who presented a second episode of thrombotic thrombocytopenic purpura (TTP). She was treated with fresh frozen plasma infusions and 14 plasma exchange (PE) sessions without response. Therefore a second-line therapy was started, associating a weekly cycle administration of vindesine (Vds) 2 mg/m2 and rituximab (R) 375 mg/m2. Five cycles of this association plus one cycle of R exclusively, were administered. After the third course, biological signs of improvement were observed and complete normalization of blood cell counts and other specific parameters was seen after 8 weeks. From the beginning of her second relapse we detected a severe deficit (<5%) in von Willebrand-cleaving factor (ADAMTS13) associated to the presence of ADAMTS13 inhibitors. The combined treatment induced an improvement in ADAMTS13 values without detectable inhibitors. After 21 months of follow-up the patient was well, without signs of relapse but ADAMTS13 values were still under normal, which may be an unfavorable prognostic factor. PE is the treatment of choice for acquired idiopathic TTP, but for refractory cases or TTP cases with severe ADAMTS13 values/high inhibitor titers, PE associated to an immunosuppressive treatment should be considered.

Using three different statistical tests in parallel, we showed in a preliminary study that neither mononuclear cells, CD34+ 33+ or 33- cells, nor CD34+ 38+ cells significantly correlated with engraftment kinetics following autologous blood cell transplantation (ABCT). We additionally demonstrated here, in a series of patients suffering from malignant diseases, that the graft content in CD34+ 38- cells is individually a more sensitive indicator of the earliest, as well as the latest post-ABCT trilineage hematopoietic recovery than the colony-forming units-granulocyte-macrophage and even the total CD34+ cell content. This suggests that the CD34+ 38- cell population is itself subdivided into two more subsets, one being already lineage-committed and responsible for short-term engraftment, the other containing only very primitive hematopoietic cells responsible for sustained engraftment. Strong arguments favor the probability that these subsets correspond to HLA-DR+ and DR cells, respectively. We also defined an optimal threshold value of 0.05 x 10(6) CD34+ 38- cells/kg of the patient's body weight (b.w.) above which a rapid and sustained trilineage engraftment safely occurs. In fact, infusion of lower numbers of cells seems to have a more significant impact on long-term compared to short-term neutrophil recovery and on platelet kinetics engraftment. We additionally looked for the eventual influence on engraftment time of the type of disease, and of post-ABCT administration of hematopoietic growth factors (HGF). When the type of disease appeared to have no influence on the engraftment time, posttransplant HGF administration significantly reduced the time to trilineage engraftment in patients transplanted with < 0.05 x 10(6) CD34+ 38- cells, thus justifying it in case of reinfusion of low numbers of CD34+ 38- cells. On the other hand, the administration of HGF after infusion of more than 0.05 x 10(6) CD34+ 38- cells/kg b.w. did not hasten more, or only very little, the engraftment time, thus becoming not only unprofitable for the patients but costly as well.