Background : Telomerase is a ribonucleoprotein, an RNA-dependent DNA polymerase,
which maintains telomere length by adding telomeric repeat units of TTAGGG to the
telomere end. This enzyme is essential for stability of eukaryotic chromosomes and may
be necessary for cell immortalization. To determine whether telomerase is activated in
hematologic malignancies, we measured telomerase activity in extracts of mononuclear
cells from normal donors and patients with various hematologic malignancies.
Methods : Telomerase activity was measured by using sensitive PCR based
telomerase assay (telomeric repeat amplification protocol. TRAP) in mononuclear cells
from 3 normal donors and 10 patients with various hematologic malignancies.
Results: Unlike other normal somatic tissues, telomerase activity was detected in
peripheral and bone marrow cells from normal donors and the level of telomerase
enzyme activity was not different from that of other hematologic malignancies.
Mononuclear cells from all the hematologic malignancies were positive in telomerase
activity being characterized 6 base pair laddering pattern regardless of disease types.
Conclusion : These Results indicate that telomerase may play a role in the malignant
transformation of hematopoietic cells and that this enzyme may be activated even in
normal mononuclear cells. Further studies to determine the mechanism and the biological
significance of telomerase activity in normal mononuclear cells should be warranted.

Keywords: Telomerase, Normal mononuclear cells, Hematologic malignancies