Flow cytometric detection of growth factor receptors in autografts and analysis of growth factor concentrations in autologous stem cell transplantation: possible significance for platelet recovery

In order to improve prediction of hematopoietic recovery,we conducted a pil ot study, analyzing the significance of growth factor receptor expression i n autografts as well as endogenous growth factor levels in blood before, du ring and after stem cell transplantation. Three early acting (stem cell fac tor (SCF), Flt3 ligand (Flt3) and fetal antigen 1 (FA1)) and three lineage- specific growth factors (EPO, G-CSF and thrombopoietin (Tpo)) were analyzed by ELISA in 16 patients with multiple myeloma (MM) and 16 patients with no n-Hodgkin's lymphoma (NHL). The relative number of SCF, Flt3, Tpo and G-CSF receptor positive, CD34(+) progenitor cells were measured by flow cytometr y in the leukapheresis product used for transplantation in a subgroup of 15 patients (NHL, n = 8, MM, n = 7), Three factors were identified as having a significant impact on platelet recovery, First, the level of Tpo in blood at the time of the nadir (day +7), Second, the percentage of re-infused th rombopoietin receptor positive progenitors and finally, the percentage of F lt3 receptor positive progenitors, On the other hand, none of the analyzed factors significantly predicted myeloid or erythroid recovery. These findin gs need to be confirmed in prospectively designed studies.