Density profiles and purification of chronic myeloid leukemia cells forming colonies in the PHA-leukocyte feeder assay.

Recently, PHA supplemented culture techniques have been introduced for growing colonies of myeloid leukemia cells. To prepare purified leukemic colony forming cell (CFC) suspensions for further studies, a discontinuous albumin density gradient separation method was applied to bone marrow and blood from patients with chronic myelocytic leukemia. It was found that the PHA-responding CFC were recovered, just as the leukocyte feeder layer stimulated CFC (Robinson CFC), from the light density fractions (1.056, 1.059 and 1.062 g/ml). Density profiles of the precursor cells forming colonies of Ph1 positive cells in the PHA-leukocyte feeder and Robinson assays appeared similar. T-lymphocyte progenitor cells, which also proliferate into colonies in the PHA-leukocyte feeder assay, were in majority harvested from the more dense fractions of the gradient. E-rosette tests and chromosome analysis were used to distinguish between leukemic and lymphocytic colonies. The density distributions of the PHA responsive leukemic CFC (Ph1 chromosome positive) and T-lymphocyte CFC (Ph1 negative) partially overlapped and a complete separation of leukemic and lymphocytic CFC was not achieved.