Stillman, Jacob MLopes, Francisco MLin, Jing-PingHu, KevinReich, Daniel SSchafer, Dorothy P2023-05-042023-05-042023-03-01Stillman JM, Lopes FM, Lin JP, Hu K, Reich DS, Schafer DP. Lipofuscin-like autofluorescence within microglia and its impact on studying microglial engulfment. bioRxiv [Preprint]. 2023 Mar 1:2023.02.28.530224. doi: 10.1101/2023.02.28.530224. PMID: 36909485; PMCID: PMC10002639.10.1101/2023.02.28.53022436909485https://hdl.handle.net/20.500.14038/52024This article is a preprint. Preprints are preliminary reports of work that have not been certified by peer review.Engulfment of cellular material and proteins is a key function for microglia, a resident macrophage of the central nervous system (CNS). Among the techniques used to measure microglial engulfment, confocal light microscopy has been used the most extensively. Here, we show that autofluorescence (AF), likely due to lipofuscin and typically associated with aging, can also be detected within microglial lysosomes in the young mouse brain by light microscopy. This lipofuscin-AF signal accumulates first within microglia and increases with age, but it is not exacerbated by amyloid beta-related neurodegeneration. We further show that this lipofuscin-AF signal within microglia can confound the interpretation of antibody-labeled synaptic material within microglia in young adult mice. Finally, we implement a robust strategy to quench AF in mouse, marmoset, and human brain tissue.enThe copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY 4.0 International license.Attribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/NeurosciencemicrogliaPreprintbioRxiv : the preprint server for biology