Compositions and kits for diagnosing and prognosing Alzheimer's Disease (AD) in a human patient include a binding agent such as a monoclonal antibody for a biomarker conjugated to a detectable moiety such as a fluorophore, wherein the biomarker is chosen from CD11c, CD59, CD91, and CD163 and other phagocytosis-related molecules. Further compositions and kits employ panels of fluorophore-conjugated monoclonal antibodies for biomarkers including scavenger receptors. Methods for determining the relative expression of biomarkers, diagnosing AD, and determining the efficacy of AD therapeutic candidates such as phagocytosis-promoting agents and scavenger receptor agonists also appear.