Some applications of microspheres in flow cytometry.

Microspheres of latex ranging from 0.1 to 10 microns in diameter are nowadays commercially available. Labelled with different fluorochromes, they are good standards to check the optical path and to calibrate flow cytometers. The kits available contain microspheres highly selected with a precise size and a narrow distribution, so as to allow an easy alignment of instruments. Mixed with the cell preparations, microspheres may be used as an internal standard, in order to compare samples from day to day. Phagocytic activity has been investigated after incubation of cells with fluorescent microspheres. Covalently bound to ligands such as antibodies, microspheres become a powerful and specific reagent to label cell surface antigens. The positive signal is enhanced, allowing the detection of poorly represented epitopes. This paper reviews some examples of these applications published in the flow cytometry field.