A cell preparation method allowing subcellular localization of cholesterol and phosphocholine with imaging TOF-SIMS

Imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used for characterization and subcellular localization of membrane lipids in leukocytes adhering to glass surfaces. The cells were prepared by freeze drying in 0.15 M ammonium formiate at pH 7.2-7.4. Imprints of the cells were made on silver foil, and the silver surface was analyzed by imaging TOF-SIMS. TOF-SIMS spectra were recorded by scanning the primary ion beam over the analysis area and acquiring positive mass spectra of the ions leaving the surface. The relative brightness of each pixel within the analysis area reflects the signal intensity of a selected ion in that pixel. Data was collected separately at high mass resolution m/Deltam > 7000 and at high lateral resolution (greater than or equal to 0.5 mum). This cell preparation procedure allows localization of cholesterol and phosphocholine in surface-adhering cells. (C) 2003 Published by Elsevier Science B.V.