Localization of monoclonal B‐cell populations through the use of Komogorov‐Smirnov D‐value and reduced chi‐square contours

Abstract In this study three different flow cytometric analysis techniques are woven together into a single system that permits improved detection of small percentages of monoclonal B cells in a milieu of either normal blood leukocytes or bone marrow cells. This analysis is an extension of the concept of clonal excess, which is used to detect the presence of a tumor that is a clonal expansion of B cells expressing either kappa or lambda light chains. The technique also utilizes “multiple list‐mode processing,” which is defined in this context as the simultaneous analysis of two or more listmode files that share one or more common parameters. This type of data structure enables the segmentation of two parameter light scatter displays into regions from which numerous kappa and lambda histograms subsequently can be analyzed for their respective Komogorov‐Smirnov D‐values or R‐values (reduced chi‐square value). The final technique makes use of a calculated parameter display system. Superimposed on the light scatter dot density plot are D‐value or R‐value contours. The contours target the location of the population that is abnormal, thus providing information for setting optimal bitmap gates for clonal excess studies, other phenotypic analyses, or cell sorting. In experiments using model systems, the sensitivity of this assay is estimated to be between 0.25% and 2.5%. The technique's distribution information and sensitivity may prove useful for staging, treatment monitoring, and relapse detection of B‐cell leukemia and lymphoma. This application illustrates the potential of combining multiple listmode processing and calculated parameter display to expand the effective dimensionality of listmode data.