OBJECTIVETo study telomerase activity (TA) and its variation in bone marrow mononuclear cells from patients with myelodysplastic syndrome (MDS) at different stages in comparison with normal bone marrow cells and leukemic cells.

METHODSThe TA was semi-quantitatively determined in mononuclear cells from 20 normal bone marrow samples, 21 patients with MDS at different stages and 32 cases of acute leukemia by using a polymerase chain reaction-enzyme linked immuno-sorben assay (PCR-ELISA) kit.

RESULTSThe TA in normal bone marrow cells was in the range of 0 to 0.3 units (U) with a mean of 0.11 +/- 0.08 U. Among them, 3 samples were considered positive in accordance with the standard recommended by the kit's pamphlet. In bone marrow cells from patients with acute leukemia, the TA was ranging from 0 to 0.96 U with a mean value of 0.42 +/- 0.26 U. The positive rate was 78.1% which was significantly different from that in normal bone marrow (BM) (P < 0.01). In case of myelodysplastic syndrome, the average level of TA was 0.27 +/- 0.19 U (ranging from 0 to 0.97 U) with a positive rate of 66.7%. In comparison with normal BM cells, the difference was significant (P < 0.05). Particularly, the MDS high-risk subgroup exhibited a significantly higher activity of telomerase (P < 0.05). In comparison with INT-1 and INT-2 subgroups in MDS patients based on international prognostic scoring system (IPPS), the difference in TA was also significant (P < 0.05). The abnormality in cell karyotype was not correlated with TA.

CONCLUSIONThe normal bone marrow cells demonstrate TA at a marginal level while a remarkably increasing level may be seen in acute leukemia patients. The BM cells from MDS patients display a moderate TA among which the high risk MDS subgroup with a poor prognostic IPPS score exhibited markedly higher TA.