Expression of the CSF-1 gene in the blast cells of acute myeloblastic leukemia: Association with reduced growth capacity

Myelopoietic growth factors are known to influence the growth in culture of malignant blast cells from human Acute Myeloblastic Leukemia (AML). We have used cDNA clones for the factor CSF‐1 and its receptor fms to study DNA and RNA from the blasts of 25 AML patients. The CSF‐1 gene was always in the germline configuration. CSF‐1 mRNA was found in about half the blast populations. The cells were also studied for their growth properties in culture. A highly significant association was found between CSF‐1 expression and poor growth in suspension culture. Most blast populations expressed fms; the number of fms expression negative samples was too small to permit the detection of any association between fms expression and growth or any interaction between the effects of the expression of the growth factor and its receptor. We propose that CSF‐1 may be an important part of the mechanism determining the balance between self‐renewal and determination in AML blast clones.