Immunohistochemical location of telomerase in lymphoma malignum in dogs

Telomerase is a ribonucleoprotein enzyme responsible for the protection of telomeres - structures which play a key role in stabilizing chromosomes. Its presence assures the possibility of tissue regeneration and unlimited cell division. On the physiological level telomerase activity is present in germline cells, embryonic tissues and some hematopoetic stem cells and, on a pathological level, in neoplastic cells. Its expression causes uncontrolled cell proliferation and may be a characteristic marker of neoplastic transformation and tumor progression. The aim of the study was to present the presence of telomerase in neoplastic lymphocytes in cases of lymphoma malignum in dogs. Cytoimmunological procedure with Telomerase (catalytic unit) NCL-L-hTERT (Novocastra Ltd product) was used to locate telomerase in malignantly transformed lymphocytes and in normal lymphocytes. The study indicated that telomerase is not present in normal lymphocytes. Higher levels of telomerase were observed in cenroblastic and immunoblastic lymphoma cells, compared with lower amounts of the enzyme in lymphoma malignum lymphocyticum B cells. A distinct presence of the enzyme was also noted in lymphoma cells of skin T-receptors. The level of this ribonucleoprotein may serve as a malignancy marker of transformed lymphocytes.