A fast and reliable system for microcomputerized DNA cytofluorometry in tumour pathology.

A microcomputerized cytofluorometry system based on a Leitz MPV 3 cytophotometer, and intended for DNA measurements in tumour pathology is described. The system has been equipped with a reference channel for correction of excitation light instability. The importance of the adjustment of the epi-illumination for optimal performance of the reference channel is stressed, and a detailed description is provided. An apparatus variability well below 1% CV is obtained even during periods of marked instability of the arc-lamp. Software for conventional cytofluorometry with which about 200 cells can be measured in 20 min is presented. In addition a measuring technique where cells are not positioned, but are just passed through the excitation light spot is described. Preliminary results on cytocentrifuged specimens of human cancers indicate that this system is at least three times faster than conventional fluorometry. The increased speed of measurements considerably extends the possibilities to evaluate cell proliferation using static cytofluorometry. The measuring capacity of course is dependent upon the quality of the specimen. In well prepared cytocentrifuged specimens 1000 cells have been measured in 35 min.