[Study of Telomerase Activity in Bone Marrow Cells from Patients with Myelodysplastic Syndromes]

To study the telomerase activity in the bone marrow MNCs from patients with myelodysplastic syndromes in comparison with that in normal individuals and acute leukemia patients. The intracellular telomerase activity was semi-quantitatively examined by PCR-ELISA assay in the marrow cells of 20 normal individuals, 21 cases of myelodysplastic syndromes (MDS) and 32 cases of acute leukemia. Telomerase activity in normal marrow cells was 0 - 0.30 U, with a mean level of (0.11 +/- 0.08) U, in which 3 cases were considered positive according to the standard set by the Kit. In 32 acute leukemia patients, the mean level of telomerase activity was (0.42 +/- 0.26) U (ranged 0 - 0.96 U) with a positive rate of 78.1%, showing a significantly higher activity in acute leukemia (P < 0.01). Moderate telomerase activity was detected in 21 cases of MDS, with a mean level of (0.27 +/- 0.19) U (0 - 0.97 U) from which the positive rate was 66.7%. This value was significantly higher than that in the normal BM (P < 0.05). Moreover, a significantly higher telomerase activity was shown in the high-risk group of MDS (P < 0.05). Based on the international scoring system evaluating the prognosis of MDS (IPPS), telomerase activity in HIGH subgroup was significantly higher than that in INT-1 and INT-2 subgroup (P < 0.05). The level of telomerase activity was not correlated to the chromosome aberrations. These results show that a borderline telomerase activity could be found in normal bone marrow cells. Telomerase activity was markedly higher in acute leukemia. BM of MDS patients demonstrated a moderate telomerase activity. Higher telomerase activity could be found in high-risk group and correlated with poor prognosis.