Development and application of a rapid cell sorter.

We have further developed our rapid cell analyzer and sorter, so that we can now identify and separate functionally distinct groups of viable cells that have, or can be made to have, either different fluorescence intensities, different light-scattering characteristics, or different combinations of these two variables. In this instrument, cells are observed individually in suspension in the central stream of a very small coaxial liquid jet, as they pass through two laser beams. The jet is later broken into uniform droplets, and those droplets containing the desired cells are charged electrically and then deflected in an electric field. Several thousand cells can be processed per second. Enrichment factors of up to 500 and final purities and viabilities of 90% or more can be routinely achieved. Cell populations present in fractions as small as 1 in 10 or less can be identified. Radioisotope analytical techniques indicate that only a few thousand fluorescent molecules need be present on a cell for it to be detected. The instrument is described and various modes of operation and biological and clinical applications are discussed briefly.