Biological effects of stroma-derived factor-1 alpha on normal and CML CD34+ haemopoietic cells.
We compared the biological effects of the CXC chemokine SDF-1alpha on immunomagnetically purified CD34+ cells isolated from human normal bone marrow (NBM), leukapheresis products (LP) and patients with chronic myeloid leukaemia (CML). LP CD34+ cells showed a significantly stronger migration response to SDF-1alpha (100 ng/ml) than CD34+ cells isolated from the peripheral blood (PB) of CML patients (P < 0.05). The chemotactic response to SDF-1alpha was also reduced in CML BM CD34+ cells in comparison to NBM CD34+ cells but the observed differences were not statistically significant. In analogy to normal CD34+ cells circulating CML PB CD34+ cells were less responsive to SDF-1alpha than their BM counterparts (P < 0.05). Furthermore, SDF-1alpha elicited similar concentration-dependent growth suppressive effects on normal and CML CD34+ cells (P > 0.05) in colony-forming cell assays. We then demonstrated that SDF-1alpha triggers intracellular calcium increases in CD34+ cells and there were no differences in the time course and dose response characteristics of normal and CML CD34+ cells. The reduced migration response to SDF-1alpha in CML CD34+ cells was not due to a down-regulation of the SDF-1alpha receptor CXCR-4 as flow cytometric analysis revealed similar CXCR-4 expression levels on NBM, LP, CML PB and CML BM CD34+ cells (P > 0.05). Finally, no differences in the modulation of CXCR-4 levels in response to SDF-1alpha and serum were observed in CML and normal CD34+ cells. Our data suggest that the impaired chemotactic response of CML CD34+ cells to SDF-1alpha is not caused by a lack or complete uncoupling of CXCR-4, but may be due to an intracellular signalling defect downstream of the receptor.
Dürig
J
J
Department of Haematology, University Hospital Essen, Germany.
Rosenthal
C
C
Elmaagacli
A
A
Heyworth
C
C
Halfmeyer
K
K
Kasper
C
C
Novotny
J
J
Dührsen
U
U
D018941:Antigens, CD19 / Q000032:analysis; D018952:Antigens, CD34 / Q000032:analysis*; D001402:B-Lymphocytes / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000494:pharmacology*; D002630:Chemotactic Factors / Q000494:pharmacology; D016044:Fusion Proteins, bcr-abl / Q000032:analysis; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007937:Leukapheresis; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism / Q000473:pathology*; D015260:Neprilysin / Q000032:analysis; D019718:Receptors, CXCR4 / Q000378:metabolism*; D013234:Stem Cells; D014410:Tumor Stem Cell Assay; D015854:Up-Regulation
D018941:Antigens, CD19; D018952:Antigens, CD34; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D002630:Chemotactic Factors; D019718:Receptors, CXCR4; D016044:Fusion Proteins, bcr-abl; D015260:Neprilysin; D002118:Calcium