Validation of a modified cryopreservation method for leukemic blasts for flow cytometry assessment

BACKGROUNDCryopreservation, a common method for storing human cells, has advantages when cells are used in retrospective studies of selected cell populations. Frozen lymphocytes can be used for tissue typing, for monitoring cell-mediated immunity, and for various immunological tests. Our report describes an efficient, simple and inexpensive method for cryopreservation of human acute leukemia cells.METHODSLeukemia cells from 20 newly diagnosed cases were frozen at -80°C after cryopreservation with 5% dimethysulfoxide and then assayed by flow cytometry for antigen expression determined by monoclonal antibodies at different time intervals.RESULTSAll cases had viability above 75% at presentation. After 4 weeks, 91% of pre-B ALL, 88% of T-ALL, 100% of AML, and 100% of biphenotypic aliquots had viability over 75%. Viability continued to be reliably above 75% at 6 weeks from cryopreservation.CONCLUSIONWe confirm that the method does not significantly alter the viability of cells and it preserved the antigenic expression of leukemia cells.