The use of a microcomputer to analyse differences between histograms derived from flow cytofluorimetric measurements

Computer programs which aid the interpretation of histograms of fluorescence intensity obtained by flow cytofluorimetry are described. The methods employed have high reproducibility when used to estimate the proportion of cells contained in a subset of the population which is distinguishable by some degree of enhancement of fluorescence intensity, e.g. the lymphocyte subset in the peripheral blood mononuclear cells stained immunocytochemically with a monoclonal antibody, or for detection of those cells that have undergone activation by demonstrating an increase in cellular RNA after stochiometric staining with acridine orange. The influence of inter-observer variability and of extraneous fluorescence spikes caused by cell culture debris has been investigated, and guidelines are set out for the use of the method. The method can be used efficiently by relatively unskilled operators to obtain highly reproducible results.