beta-Amyloid peptide (A beta), a major component of senile plaques, the formation of which is characteristic of Alzheimer's disease (AD), is believed to induce inflammation of the brain mediated by microglia, leading to neuronal cell loss. In this study, we performed an oligonucleotide microarray analysis to investigate the molecular events underlying the A beta-induced activation of macrophages and its specific suppression by the A beta-specific-macrophage-activation inhibitor, RS-1178. Of the approximately 36,000 genes and expressed sequence tags analyzed, eight genes were specifically and significantly upregulated by a treatment with interferon gamma (IFN gamma) and A beta compared to a treatment with IFN gamma alone (p