CIRCULATING COLONY-FORMING CELLS IN CHILDHOOD LEUKEMIA

Abstract

Serial in vitro agar culture of peripheral blood was performed in children with acute leukemia in various stages of disease. In acute lymphocytic leukemia, in contrast to the depressed colony-forming cells (CFC) in the bone marrow, circulating CFC were greatly increased in untreated patients and patients in relapse. CFC returned to normal after successful remission induction and while on maintenance therapy. Depressed CFC in marrow and continuous increased CFC in blood after vincristine and prednisone induction may indicate incomplete remission in spite of morphological criteria of remission. An increase of CFC in peripheral blood was also observed transiently during the early phase of recovery from marrow depression by either infection or chemotherapy. An increase in circulating CFC, before clinical and peripheral blood evidence of relapse, has been observed in one patient off therapy for 11 months. Patterns of in vitro growth may also help to distinguish different types of leukemias, especially the undifferentiated leukemias which fail to demonstrate cytochemical markers. A pattern of CFC and colony-stimulation activity similar to “pre leukemia” in adults was also observed in children with Fanconi's aplastic anemia. In conclusion, we believe agar culture of peripheral blood, as well as bone marrow, to be useful in diagnosis, confirming the completeness of remission, and assessing prognosis in children with leukemia.