Telomere dysfunction of lymphocytes in patients with Alzheimer disease

Objective: The objective of this study was to investigate the telomerase activity of phytohemagglutinin-activated lymphocytes from patients with Alzheimer disease. Background: There is impairment of immune function in patients with Alzheimer disease, and the perturbation of immune system is involved the pathogenesis of Alzheimer disease. However, the mechanism of the impairment is unclear so far. Methods: We analyzed telomerase activities of phytohemagglutinin-activated lymphocytes from 187 cases of patients with Alzheimer disease, 53 cases of patients with vascular dementia, and 80 cases of age-matched healthy controls, respectively. Telomerase activity was measured using the telomeric repeat amplification protocol-based telomerase polymerase chain reaction enzyme-linked immunosorbent assay. We also detected the proliferation activity of peripheral blood mononuclear cells from 10 cases of patients with Alzheimer disease or 10 cases of age-matched healthy controls by [³H] thymidine incorporation. Results: Telomerase activity of phytohemagglutinin-activated lymphocytes in Alzheimer disease patients was significantly elevated compared with healthy controls (P <0.01) and vascular dementia patients (P <0.01), respectively. There was significant statistical correlation between the telomerase activities of lymphocytes and the degree of dementia in Alzheimer disease patients. The proliferation activity of peripheral blood mononuclear cells to phytohemagglutinin was significantly decreased in Alzheimer disease patients compared with age-matched healthy controls (P <0.01). Conclusions: Our data suggest that there could be an accelerated telomere dysfunction in lymphocytes of Alzheimer disease patients, which induces the increase of telomerase activity and the decrease of proliferation activity of lymphocytes, and subsequently results in the impairment of immune function in Alzheimer disease patients.