SOLID-PHASE CYTOMETRY FOR DETECT OF RARE EVENTS

We describe a simple and rapid laser scanning device for solid phase c ytometry This system can detect and count fluorescent cells over a 22 mm diameter surface (membrane or glass circle) as well as quantify the fluorescence that they emit. A comprehensive discrimination package i ncludes optical and software parameters and accurately distinguishes b etween valid signals (e.g., labelled cells) and nonspecific signals (e .g., auto-fluorescent particles and debris). Any event detected may al so be easily confirmed by visual observation after transfer of the sam ple to an epifluorescence microscope fitted with a motorized stage dri ven by the system. We show a linear relationship between the amount of fluorescein coupled to the cells and the fluorescence signal of the c ells detected. This approach is not destructive and further characteri zation of the sample may be carried out. We have been able to detect r are cellular events at a frequency of 10(-7) in 3 min. Potential appli cations include monitoring of residual disease in oncology and detecti on of virus-infected cells circulating at very ion: frequencies. Cytom etry 27:336-344, 1997. (C) 1997 Wiley-Liss, Inc.