Cross-correlation for flow cytometric histogram background subtractions

Background subtraction is a widely encountered problem in flow cytometry ap plications for which the currently available analysis techniques are unsati sfactory. The 99% division line method, also referred to as the threshold o r marker method, is widely used because it is computationally simple but it has poor accuracy and tends to underestimate the percentage of positive ce lls when there is overlap between histograms. Model-based approaches are pr eferred when there are overlapping peaks, but these methods require curve f itting and strong assumptions regarding the shape of the underlying distrib utions. This report assesses a mathematically rigorous, computationally fac ile, non-parametric technique called cross correlation for the background s ubtraction problem. A metric, positivity, derived from cross correlation is shown to overcome the disadvantages of both the 99% division line and mode l-based methods without compromise. (C) 2000 Elsevier Science BN. All right s reserved.