The Role of SDF-1/CXCR4 in the Procession of Auto-Stem Cell Transplantation of Multiply Myeloma Patients.

CXCR4, receptor of the chemokine stromal derived factor-1 (SDF-1), is expressed on CD34⁺ cells, and has been implicated in the process of CD34⁺ cell migration and homing. We studied the mobilization of CD34/CXCR4 cells and the plasma levels of SDF-1 and sgp130 in 22 patients, 11 acute Leukemia, 5 non-Hodgkin’s lymphoma, and 6 multiply myloma respectably, receiving cyclophosphamide (Cy) and plus G-CSF, or Mitoxantrone(Mit) and Cytarabine plus G-CSF for peripheral blood stem cell (PBSC) mobilization and autotransplantation. We observed lower plasma levels of SDF-1 in PBSCs compared with premobilized PB and bone marrow samples. The average levels of SDF-1 and sgp130 were 24.67±5.58ng/ml and 106.2±16.4ng/ml respectively while the level of SDF-1 as well as sgp130 decreased to 14659±2.11ng/ml(p<0.05)and 58.8±29.1ng/ml(p<0.05) respectively on day when PBSC was collected after mobilization. SDF-1 levels in the apheresis collections of the “good mobilizers” (patients who collected a minimum of 2 × 10⁶ CD34⁺ cells/kg in one to three PBSC collections) were significantly lower than the apheresis collections of the “poor mobilizers” (<2 × 10⁶ CD34⁺ cells/kg in the three cycles of PBSC collections; 14.82 ± 7.08 ng/ml versus 27.2 ± 8.13 ng/ml; p<0.01). The mean percentage of CD34⁺ cells expressing CXCR4 in the apheresis collections was decreased in the PBSC collections compared with premobilization values ranging from 32.09±5.39% to 22.4±5.92%. But the mean CXCR4 expression on CD34⁺ cells of the good mobilizers was not different from the expression on CD34⁺ cells of poor mobilizers. Furthermore, the levels of sgp130 closely correlated with SDF-1 levels (r = 0.87; p < 0.001); the plasma level of SDF-1 and expression of CXCR4 on the CD34⁺ cells were gradually decreased in the PB of patients during the procession of mobilization; low plasma levels of SDF-1 turned out with good mobilization outcome, and the levels of SDF-1 correlated with sgp130, suggesting an association of these cytokines in mobilization of CD34⁺ cells.