Abstract: This invention relates to a method for the detection of rare events which are events occurring at a frequency of less than one in 104. It is particularly useful in detecting events at frequencies of one in 105 and one in 106. The method employs one or more first markers that are specific for the rare event particle each of which are labeled with a dye having an emission wavelength distinguishable from the other(s). The method further employs one or more second markers that are specific for a majority of the remainder of the particles present in the cell sample but are negative for the rare event particle. The second markers all are labeled with the same dye. The second markers are collectively referred to as the exclusion color. By analyzing the particles for the presence of the first marker(s) and the absence of the second markers, rare events can be detected.

Abstract: A method for automatic lineage assignment of acute leukemias. Eight four-parameter list mode data files are acquired with a flow cytometer in the following sequence: 1. unstained; 2. isotype controls; 3. CD10 FITC, CD19 PE; 4. CD20 FITC, CD5 PE; 5. CD3 FITC, CD22 PE; 6. CD7 FITC, CD33 PE; 7. HLADR FITC, CD13 PE and 8. CD34 FITC, CD38 PE. First, data files 3-8 are clustered employing an algorithm based on nearest neighbors. The clusters are then associated across the data files to form cell populations, using the assumption of light scatter invariance across tubes for each population. The mean positions of each cell population are compared to a decision tree which identifies normal cell populations. To identify leukemic cell populations, the algorithm eliminates normal cell populations from the data space and the remaining populations are classified as B-lineage ALL, T-lineage ALL, AML, AUL, B-CLL or unknown.