Growth factor receptor profile of CD34(+) cells in AML and B-lineage ALL and in their normal bone marrow counterparts

Leukaemic cells show a low clonogenic activity and a heterogeneous prolifer ative response to growth factors. We investigated whether this could be due to an altered expression of growth factor receptors on the leukaemic precu rsors. Receptors for G-CSF, stem cell factor (SCF), IL-3, IL-6 and IL-7 wer e detected on CD34(+) cells in AML and B-lineage ALL with monoclonal antibo dies and flow cytometry. The expression was compared with that on myeloid a nd B-lymphoid CD34(+) cells in normal bone marrow. Leukaemic CD34+ cells ex pressed the same receptors as their normal counterparts. AML and B-lineage ALL could be distinguished by the growth factor receptor profile of their C D34(+) cells. SCFR, G-CSFR and IL-6R alpha were found in AML, IL-7R in B-li neage ALL and IL-3R alpha in both. IL-3R alpha was upregulated in AML and B -lineage ALL CD34+ cells, while samples with low or high expression were pr esent for the other receptors. This variable expression could correlate wit h the heterogeneous response of leukaemic cells to growth factors. Function al studies on isolated CD34(+) cells are needed to investigate this further .