BETA-AMYLOID PROTEIN ENHANCES THE MITOGEN-INDUCED CALCIUM RESPONSE INCIRCULATING HUMAN-LYMPHOCYTES

The role of beta-amyloid in Alzheimer's disease and its cellular mecha nism of action on neurons are still unclear. There is growing evidence that beta-amyloid or its fragment, 25-35, influence neuronal calcium regulation. To investigate the effects of beta-amyloid on calcium home ostasis in man we used peripheral human lymphocytes as a model system for central neurons. Beta-Amyloid fragment 25-35 exposed to lymphocyte s for 60 s elevates the phytohemagglutinin (PHA)-induced Ca2+ rise in a dose-dependent manner. Small effects were already seen at concentrat ions as low as 50 nmol/l. Similar effects were also observed with frag ment 1-40, whereas fragments 1-28 or 12-28 did not affect the Ca2+ res ponse after PHA stimulation. Our findings support the hypothesis of an enhanced calcium response as a general feature of beta-amyloid's neur otoxicity. The lymphocyte seems to be a valuable model to study this e ffect in man.