[Clonogenic cells of acute leukemia secondary to myeloproliferative and myelodysplastic syndromes].

PURPOSE

To assess if the in vitro behaviour of leukaemic colony-forming units (CFU-L) from secondary leukaemias is similar to that of the de novo acute myeloblastic leukaemia. An attempt was also made to verify if such behaviour correlated with the characteristics of the disease or with the cell-surface markers of the leukaemic population.

PATIENTS AND METHODS

The study was carried out on 21 patients with secondary acute leukaemia (12 had previous myelodysplastic syndrome, MDS-AL, and 9 had previous chronic myeloproliferative syndromes, MPS-AL). Peripheral blood mononucleated cells were cultured on methyl-cellulose with MCL-PHA stimulation. The dishes were examined after 7 days of incubation in humid 37 degrees C environment with 5% CO2. Direct or indirect immunofluorescence was used for the immunophenotypic analysis and the patients were divided in two groups: 1) immature phenotype, which include those cases expressing only precursor (CD34) or pan-myeloid (CD33/13) antigens, and (2) mature phenotype, comprising the caes with granulomonocytic (CD15, CD14), erythroid (glycophorin) or megakaryocytic (CD61) differentiation. The statistical analysis was done with the BMDP programme.

RESULTS

Up to 95% of the secondary acute leukaemias proliferate in vitro, as opposed to 82% of the de novo ones, the difference not being significant (p = 0.14). Successful cell showing was clearly superior in the former (p = 0.02), mostly due to higher proliferation of the MPS-AL cells. Neither the clinico-biologic characteristics of the patients nor the phenotype of the blast cells correlated with the in vitro behaviour of CFU-L. Only CD19 antigen expression and nuclear TdT provided a lesser in vitro growth (p = 0.05 and p-0.06, respectively).

CONCLUSION

In general terms, secondary leukaemias, especially MPS-AL, show higher in vitro growth than de novo acute myeloblastic leukaemias.