Effect of intensified chemotherapy on the pluripotent haematopoietic progenitor cells CFU-GEMM in adult acute lymphoblastic leukaemia

In order to analyse the short-term and long-term effects of intensified induction chemotherapy, the frequency, cellular composition and proliferative state of the pluripotent haemopoietic progenitor cells CFU-GEMM was investigated in a total of 35 patients with acute lymphoblastic or acute undifferentiated leukaemia at diagnosis, as well as during and after therapy. At diagnosis, the number of CFU-GEMM/ml bone marrow aspirate was significantly reduced to 12.1 (95% confidence interval 2.1-70) as compared to healthy controls (50.4/ml; 95% confidence interval 66-3846/ml). While immediately after the end of induction therapy, the respective values for CFU-GEMM were still decreased (30.4/ml; 95% confidence interval 8.4-108); values not significantly different from normal were reached within the following 4 weeks. During and after cessation of maintenance therapy again no significant deviation from normal values was observed. Immunological analysis of single colonies revealed that during the early phase after remission induction only 60 +/- 7% of mixed colonies contained megakaryocytic cells (normal 86 +/- 3%; P less than 0.01) while normal values were found during and after maintenance therapy. Cell cycle analysis disclosed highly increased proliferative activity of pluripotent progenitor cells during marrow regeneration after induction therapy as well as during maintenance therapy, but a return to the resting state after cessation of maintenance therapy. It is concluded that this intensive chemotherapy regimen does not result in any apparent long-term damage to the pluripotent haemopoietic progenitor cells.