Confocal scanning fluorescence microscopy: a new method for phagocytosis research.

An important new method for phagocytosis research, confocal scanning fluorescence light microscopy (CSFM), is demonstrated using fluorescent microspheres ingested by murine macrophages. CSFM, in combination with Nomarski differential interference contrast microscopy (DIC), can resolve microspheres inside cells from microspheres attached to the surface of cells. Further, combined CSFM and DIC images can quantitate phagocytosis by individual cells aggregated together. No other method offers these capabilities. A comparison of CSFM and conventional epifluorescence light microscopy (EFM) images shows that CSFM produces significantly higher-resolution images of microspheres than EFM, primarily because CSFM excludes the out-of-focus light artifacts of EFM.