TELOMERE SHORTENING IN LEUKEMIC-CELLS IS RELATED TO THEIR GENETIC ALTERATIONS BUT NOT REPLICATIVE CAPABILITY

We compared telomere length in donor leukemic cells and corresponding established cell lines from three patients with chronic myeloid leukem ia (CML) and three with acute lymphoblastic leukemia (ALL) to study th e relation between the immortalization capacity of hematologic neoplas ms and telomere length. Six of the seven established leukemia cell lin es (four CML and two ALL) carried additional chromosome changes and ha d shorter telomere repeats than those of the donor patients' leukemic cells; the remaining ALL line showed no significant difference in telo mere length between fresh leukemic cells and the corresponding cell li ne. Thus, most established leukemic cells lose effective telomerase ac tivity during the process of establishment, and reduction in telomere length of established leukemic cells appeared to be associated with th e presence of additional chromosome changes.