Paired helical filaments contain small amounts of cholesterol, phosphatidylcholine and sphingolipids

By using qualitative and quantitative high-performance thin layer chromatography (hpTLC) we found lipids associated with purified Alzheimer's (AD) paired helical filaments (PHF) in an amount of 1.4 +/- 0.2% of the total anhydrous mass. Compared to normal brain tissue these lipids have an unusual lipid class composition. The most prominent lipid classes were phosphatidylcholine (PC), cholesterol (CH), galactocerebrosides (GC) and sphingomyelin (SM). In addition, the use of micro high-performance liquid chromatography (HPLC) in combination with matrix-assisted laser desorption and ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) allowed the determination of the molecular species of the polar membrane lipid classes present in PHF. The lipid pattern of intracellular PHF shows many characteristics of the conserved lipid pattern previously described for extracellular amyloid fibrils, suggesting similarities in their pathway of formation.