Elevation of platelet activation markers and chemokines during peripheral blood stem cell harvest with G-CSF

The kinetics of peripheral blood stem cell mobilization in response to recombinant human granulocyte colony-stimulating factor is well established. However, there have been few investigations of platelet activation markers during peripheral blood stem cell harvest. We measured the levels of the platelet activation markers, chemokines, and soluble factors in plasma obtained from patients undergoing peripheral blood stem cell harvest. The number of leukocytes, CD34(+) cells, neutrophils, monocytes, and lymphocytes peaked on day 5 after granulocyte colony-stimulating factor treatment, but the numbers of eosinophils and basophils showed no significant change. Regulated on activation normally T-cell expressed and secreted (RANTES) level increased through day 10, and the monocyte chemotactic peptide-1 (MCP-1) level peaked on day 5. Platelet counts continued to increase through day 10. The level of thrombopoietin significantly increased on day 3, peaked on day 5, and decreased slightly by day 10. The levels of soluble CD40 ligand and soluble P-selectin increased up to day 5. The platelet-derived microparticle level peaked on day 5, and then began to decline. CD34(+) cell numbers significantly correlated with those of leucocytes, neutrophils, monocytes, and lymphocytes, as well as levels of MCP-1, and the CD34+ cells exhibited changes similar to platelet-derived microparticles. The patterns of change in MCP-1, platelet-derived microparticles, and the CD34(+) cell count are similar in that each peaks on day 5 and decreases thereafter. Further study is required to determine if a cause-and-effect relationship in their pattern of change exists among them.