Flow cytometric analysis of G-CSF receptors on normal white cells and leukemic cells

In treatment of leukemia with granulocyte colony stimulating factor (G-CSF), the possibility is that G-CSF receptors on leukemic cells lead to activate its proliferation in response to G-CSF. Therefore, it is useful to know the proportions of leukemic cells with receptors for G-CSF. We used flow cytometry to estimate the proportion of such cells and normal granulocytes with G-CSF binding activity. Recombinant human G-CSF was labeled with fluorescein isothiocyanate. Granulocytes showed higher binding to the G-CSF than lymphocytes. Leukemic cells obtained from 17 to 21 patients with AML bound specifically to G-CSF, but leukemic cells with lymphoid malignancies did not. Our results showed positive correlation with date obtained by the isotopic G-CSF receptor assay. With this method, leukemic cells need not be isolated; they can be distinguished from lymphocytes or granulocytes on the cytometry screen. Radioisotopes are not needed. It is judged to be practical for the clinical laboratory.