MOBILIZATION OF PERIPHERAL STEM-CELLS AFTER HIGH-DOSE CHEMOTHERAPY IN MULTIPLE-MYELOMA

The response of Multiple Myeloma patients on PBSC mobilizing treatment with high dose Melphalan or Endoxan is normal in one part of the patients and dissatisfactory in the other. In order to identify cellular traits being responsible for this alternative outcome, in vitro colony growth in the short term assay was analyzed. In one group, low rates of colonies grow after stimulation, and normal rates in the other; size of the immature CD34+ hematopoietic cell compartment is usually in the normal range in both instances. We show that impaired stimulation originates from dysfunction of monocytes. Comparison with the PBSC mobilization after high dose chemotherapy (HDC) reveals that impaired monocyte function entails both bad in vitro stimulation and slow recovery. Furthermore in some cases with good progenitor stimulation, recovery was also hampered, which indicates that in these cases other factors may be involved.