INVITRO MATURED HUMAN MACROPHAGES EXPRESS ALZHEIMERS BETA-A4-AMYLOID PRECURSOR PROTEIN INDICATING SYNTHESIS IN MICROGLIAL CELLS

Microglia which are consistently associated with alzheimer's disease (AD) senile plaques are part of the mononuclear phagocyte system. In-vitro matured human monocyte-derived macrophages feature many immunological characteristics of microglia. We found strong constitutive expression of Alzheimer's beta-A4-amyloid precursor protein (AAP) in human mononuclear phagocytes after terminal in-vitro maturation from monocytes to macrophages. Amyloid has previously been found to be associated with microglia in AD brains, however, it remained unclear whether the material was synthesized in or had been phagocytosed by the cells. The findings presented here support the assumption that brain microglia may contribute to AAP synthesis in AD brain.