Ion microanalysis of cells.

The application of ion microanalysis (IMA) to the chemical characterization of freeze-fixed, freeze-dried cells is reviewed. Particular emphasis is given to pathological studies involving the determination of the chemical composition of isolated cells (e.g. rabbit alveolar macrophages--RAMs) exposed in vitro to toxic species (e.g. Pb3O4 particles). Ion microscopic results indicated that lead from Pb3O4 migrated into the RAMs and subsequently formed phosphorous-containing compounds. Quantitative comparisons of the relative concentrations of physiologic elements in Pb3O4-treated versus control RAMs also were made using ion microanalytical techniques. The Pb3O4 results illustrate that the three-dimensional analysis capabilities of the IMA may be exploited for the in situ observation of the penetration of xenobiotic agents into cell interiors and their subsequent intracellular chemistry. The potential advantages of ion microanalysis for the characterization of cells include high elemental sensitivity (including low atomic number elements and diffusible ions), broad elemental coverage, three dimensional analysis, and isotopic information. The major limitations include non-idealities of the ion sputtering process, the constraints on the lateral resolution available to identify subcellular features, and the difficulties inherent in the determination of absolute elemental concentrations.