Evaluation of hematopoiesis by granulocyte elastase after hematopoietic stem cell transplantation

To evaluate hematopoietic restoration after hematopoietic stem cell transplantation (HSCT), we sequentially monitored the post-HSCT level of granulocyte elastase (GE), a sensitive parameter of qualitative and quantitative changes in granulopoiesis. We compared it with routinely used hematopoietic recovery indices, such as leukocyte and reticulocyte count. We also compared levels of GE in the clinical administration of different colony stimulating factors (granulocyte-colony stimulating factor (G-CSF) versus macrophage-colony stimulating factor (M-CSF) and in different types of hematopoietic stem cell transplantation (allogeneic bone marrow transplantation (BMT) versus autologus peripheral blood stem cell transplantation (PBSCT)). Days to first increase of GE after HSCT were 3.0 and 2.3 days earlier than increase of leukocytes in allo-BMT and auto-PBSCT, respectively. Recovery of highly fluorescent reticulocytes and monocytes were later than recovery of GE. These results indicated that granulopoiesis after transplantation started before the increase in peripheral leucocyte count, and that GE was the earliest indicator of hematopoietic recovery. On the basis of GE level, M-CSF had the same stimulating effect on granulopoiesis as G-CSF. The nadir of GE in PBSCT was significantly higher than that in BMT, indicating continuous granulopoiesis in PBSCT. From these results, we concluded that measurements of GE can be used for the clinical evaluation of myelosuppression by different conditioning regimens as well as of granulopoiesis induced by various cytokines.