Introduction

The second half of the twentieth century witnessed remarkable developments in cytometry, which were made possible by simultaneous advances in a number of different disciplines. It is unlikely, however, that such rapid progress would have been made if the new technologies had not been embraced so enthusiastically by clinical laboratories. That routine cytometric analyses can make such a cost-effective contribution to disease diagnosis and patient management was, and is likely to continue to be, one of the strongest forces influencing innovation in cytometry. In other areas, cytometric techniques that were first established in the biomedical sciences are now being applied increasingly not only to detect and characterise cells but also to quantify soluble analytes.

Conventional clinical flow cytometers measure only the intensity of scattered and fluorescent light but research instruments exist that have the ability to measure other parameters contained in these signals (Roslaniec et al., 1997). If the extra information that can be gained from these measurements proves useful in the clinical context, the facility to measure other parameters could be incorporated in instruments for routine use.

A new generation of radically different cytometers has also just started to emerge. The Compucyte laser scanning cytometer is the first of a number of scanning instruments designed to characterise cells that are held stationary on, or in, a support medium. At present, static cytometers are perhaps not as versatile as their flow-based counterparts but they have some interesting and unique capabilities, which will ensure their wider use in the future. In recent years, laboratory bench-top analytical flow cytometers have been getting steadily smaller and some small ‘point of care’ and portable instruments are now available.