Peripheral blood blast cell progenitors in human preleukemia.

Progenitors of blast cell colonies have been identified in acute leukemia. The peripheral blood of 18 of 25 patients with preleukemic states yielded low numbers of blast cell colonies, and the colony-forming cells were in an active proliferative state when assessed using short-term exposure to tritiated thymidine. The clinical significance of blast cell colonies is uncertain, but we suggest that further analysis of this cultural abnormality may lead to a better understanding of mechanisms and management in preleukemia.