The correlation dimension identifies B-cell immunoglobulin light chain restriction in peripheral blood flow cytometry data.

The correlation dimension (D2) is a mathematical tool that quantifies dimensional properties of fractals. We set out to determine whether immunoglobulin light chain restriction (LCR) in B-cell lymphoproliferative disorders (BCLPDs) could be identified using the D2. The D2 was calculated from flow cytometry data files (FCS 2.0) from a training set of peripheral blood specimens from 22 patients with and 23 patients without BCLPD. A cutoff value derived from the training set was applied to a validation set of 69 patients with and 64 patients without BCLPD. In the training set, all BCLPDs had a D2 of less than 0.72 (CD19-gated kappa-lambda data). When this cutoff was applied to the validation set, the D2 had sensitivity and specificity values of 88% and 98%, respectively. The D2 can identify LCR in peripheral blood flow cytometry data. It offers operator-independent data analysis and may be useful in objectively quantifying differences in data distribution.