Increased cytosolic free calcium in lymphocytes of Alzheimer patients.

Free cytosolic calcium content [Ca2+]i was determined in peripheral blood mononuclear cells (PBMC) from healthy volunteers, Alzheimer's disease and multi-infarct dementia patients. Measurement of [Ca2+]i by the fluorescent dye quin-2, before and at several time intervals during incubation with phytohemagglutinin (PHA), showed a higher resting [Ca2+]i in PBMC of Alzheimer's disease patients as compared to controls and multi-infarct dementia patients. However, the addition of supra-optimal PHA doses (100 micrograms/ml) induced strikingly higher [Ca2+]i levels in Alzheimer's disease patients (1647 +/- 200 nM versus 398 +/- 27 nM in controls, and 346 +/- 40 nM in multi-infarct dementia patients). The increased [Ca2+]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 [Ca2+]i may prove diagnostically valuable.