Characterisation of the differential response of normal and CML haemopoietic progenitor cells to macrophage inflammatory protein-1alpha.
The clonogenic cells of chronic myeloid leukaemia (CML), unlike normal haemopoietic colony forming cells (CFC), are resistant to the growth inhibitory effects of the chemokine, macrophage inflammatory protein-1alpha (MIP-1alpha). Here, we tested the hypothesis that MIP-1alpha protects normal, but not CML, CFC from the cytotoxic effects of the cell-cycle active drug cytosine arabinoside (Ara-C). Using a 24-h Ara-C protection assay we showed that MIP-1alpha confers protection to normal CFC but also sensitizes CML CFC to Ara-C. The differential MIP-1alpha responsiveness was not due to a down-regulation of MIP-1alpha receptors on CML CD34+ cells as flow cytometric analysis showed similar binding of a biotinylated MIP-1alpha molecule to normal and CML CD34+ cells. Flow cytometric analysis of the MIP-1alpha receptor subtype CCR-5 revealed comparable CCR-5 expression levels on normal and CML CD34+ cells. Furthermore, culture of CD34+ cells for 10 h in the presence of TNF-alpha resulted in an increased MIP-1alpha receptor expression on both normal and CML CD34+ cells. Our data suggest that the unresponsiveness of CML CFC to the growth inhibitory effect of MIP-1alpha is not caused by a lack of MIP-1alpha receptor or total uncoupling of the MIP-1alpha responsiveness but may be due to an intracellular signalling defect downstream of the receptors.
Dürig
J
J
CRC Section of Haemopoietic Cell and Gene Therapeutics, Paterson Institute for Cancer Research, Manchester, UK.
Testa
N G
NG
Lord
B I
BI
Kasper
C
C
Chang
J
J
Telford
N
N
Dexter
T M
TM
Heyworth
C M
CM
D000293:Adolescent; D000328:Adult; D000368:Aged; D002448:Cell Adhesion; D002453:Cell Cycle / Q000187:drug effects; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D002648:Child; D003561:Cytarabine / Q000633:toxicity; D005260:Female; D005455:Fluorescent Antibody Technique; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000473:pathology*; D019402:Macrophage Inflammatory Proteins / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D014411:Neoplastic Stem Cells / Q000187:drug effects*; D019713:Receptors, CCR5 / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D054405:Chemokine CCL3; D054407:Chemokine CCL4; D019402:Macrophage Inflammatory Proteins; D019713:Receptors, CCR5; D014409:Tumor Necrosis Factor-alpha; D003561:Cytarabine