Influence of cryopreservation on human leukaemic clonogenic cells (CFU-L).

The biological and clinical significance of growth characteristics of leukaemic clonogenic cells (CFU-L) cultured from patients has been the subject of many studies. While some investigators collect leukaemic cells in large numbers from blood of untreated patients and store them in a frozen state before use in experiment, others study fresh cells. Since cryopreservation may alter the proliferation and differentiation of CFU-L, we have followed its influence and that of DMSO, used as protective agent and known to be an inducer of differentiation in leukaemic blasts, on the clonogenicity of peripheral blast cells from patients with AML and CML in blast crisis. Our data show that a short incubation with 7.5% DMSO (with or without cryopreservation) induced increase in the clonogenicity and proliferation rate of CFU-L (without morphological changes). The possible causes of these effects as well as the question of aggressivity of leukaemic blasts after the short incubation with 7.5% DMSO are discussed.