Increased cytosolic free calcium in lymphocytes of Alzheimer patients

Free cytosolic calcium content [Ca 2+] i was determined in peripheral blood mononuclear cells (PBMC) from healthy volunteers, Alzheimer's disease and multi-infact dementia patients. Measurement of [Ca 2+] i by the fluorescent dye quin-2, before and at several time intervals during incubation with phytohemagglutinin (PHA), showed a higher resting [Ca 2+] i in PBMC of Alzheimer's disease patients as compared to controls and multi-infract dementia patients. However, the addition of supra-optimal PHA doses (100 μg/ml) induced strikingly higher [Ca 2+] i levels in Alzheimer's disease patients (647 ± 200 nM versus 398 ± 27 nM in controls, and 346 ± 40 nM in multi-infarct dementia patients). The increased [Ca 2+] i concentration was also found after a specific stimulation with a monoclonal anti-CD3 antibody. The results may have important implications in understanding the pathophysiology of Alzheimer's disease and suggest that [Ca 2+] i may prove diagnostically valuable.