Drug-induced agranulocytosis: bone marrow granulocytic progenitor cells.

Bone marrow CFU-GM and cluster forming cells were studied in ten patients in different stages of drug-induced agranulocytosis using a methylcellulose cell culture technique in vitro. In the aplastic phase of the disease (A), the number of both CFU-GM and cluster forming cells was decreased in comparison to normal values. In the regenerative phase of the disease (R), the number of both granulocytic progenitors increased but did not reach normal values. In patients considered to be recovered from acute agranulocytosis (Rec), a decreased number of progenitors persisted indicating residual damage at this granulocytic cell level. It is suggested that agranulocytosis is due to isolated damage of granulocytic cells and predictable cascade of events within different cell compartments could be used as an in vivo model for investigation of the regulation of granulopoiesis.