Evaluation of thrombopoiesis kinetics by measurement of reticulated platelets and CD34(+) cell subsets in patients with solid tumors following high dose chemotherapy and autologous peripheral blood progenitor cell support

Background and Objectives. The transplantation of mobilized peripheral prog enitor cells has resulted in shortening of neutrophil and platelet engraftm ent times following high-dose chemotherapy. Since reticulated platelet perc entage (RP%) has been established as a measure of bone marrow platelet prod uction, we performed this type of analysis on the thrombopoietic compartmen t during transplant-related chemotherapy. Design and Methods. Kinetics of thrombopoiesis of 19 patients with solid tu mors undergoing a single or double autologous peripheral blood progenitor c ell transplant was characterized by evaluating the level of RR The correlat ion between CD34(+) cell subsets and the time of highest percentage of RP w as also evaluated. Results. The percentage of RP increased from day +8 after single transplant reaching the peak (3.4%) at day +10. In the group of patients receiving do uble transplant, the peak RP value of observed after the second transplant is not significantly different from that observed after the first transplan t (3 vs 3.7%). In a subgroup of patients both the number of CD34+ cells/Kg infused and the percentage of CD34(+)CD61(+) cell subsets correlated with t he day of RP peak. Interpretation and Conclusions. These results suggest that RP measurement i s an early indicator of engraftment. Additionally, the observation that RP percentage is high at the time of platelet transfusion in 13 out of 20 case s of transfusions (the 7 cases with low RP value being transfused during th e period of obligate thrombocytopenia) suggests that the evaluation of this parameter, together with the platelet count, can be used to monitor, the n eed for platelet transfusion. (C) 2001, Ferrata Storti Foundation.