Cytosolic free [Ca2+] in mononuclear blood cells from demented patients and healthy controls

There is increasing evidence that the neurodegenerative processes in Alzheimer's disease (AD) may be related to alterations in calcium homeostasis and that these metabolic changes are not necessarily restricted to the central nervous system. However, previous studies investigating [Ca2+]i in fibroblasts, lymphoblasts, platelets and lymphocytes of AD patients gave inconclusive results, since increase, decrease and no alteration in [Ca2+]i were found in AD patients compared with controls. With respect to the importance of establishing altered Ca2+ homeostasis in peripheral cells, we have investigated [Ca2+]i in circulating mononuclear cells of patients with AD, multi-infarct dementia, age-associated memory impairment and healthy controls. [Ca2+]i was evaluated using the fluorescent dye fura-2 before and during stimulation with phythaemagglutinin (PHA). In our study we failed to find major differences in resting [Ca2+]i and in response to stimulation with 25 micrograms/ml and 100 micrograms/ml PHA in cells of AD patients as compared with all other groups investigated. There was only a tendency towards a decrease in [Ca2+]i in AD after stimulation with PHA. Thus the present findings suggest that [Ca2+]i evaluation in mononuclear cells does not have diagnostic value in discriminating AD patients from other demented patients. However, there might be some difference in [Ca2+]i values between early- and late-onset AD, which could have pathophysiological importance.