Abstract
The proliferative response of normal and leukemic human granulocytic cells to stimulation by varying concentrations of the normal regulator, colony-stimulating factor (CSF), was determined by cluster counts in agar cultures of 150 blood or marrow specimens stimulated by monkey lung conditioned medium. Acute myeloid leukemic cells were slightly more responsive than normal at low concentrations of conditioned medium, but chronic myeloid leukemic cells were slightly, less responsive at all concentrations. Marrow cells from acute leukemic patients in remission exhibited a normal pattern of responsiveness. Average plasma CSF levels in leukemic patients were two to three times higher than the concentration of CSF in cultures maximally stimulated by monkey lung conditioned medium. The observed responsiveness of leukemic cells to stimulation by CSF-containing material is further evidence in support of the conclusion that most myeloid leukemias in man are conditioned, rather than autonomous, neoplasms.
