Automated pattern-guided principal component analysis vs expert-based immunophenotypic classification of B-cell chronic lymphoproliferative disorders: a step forward in the standardization of clinical immunophenotyping

Abstract

Immunophenotypic characterization of B-cell chronic lymphoproliferative disorders (B-CLPD) is becoming increasingly complex due to usage of progressively larger panels of reagents and a high number of World Health Organization (WHO) entities. Typically, data analysis is performed separately for each stained aliquot of a sample; subsequently, an expert interprets the overall immunophenotypic profile (IP) of neoplastic B-cells and assigns it to specific diagnostic categories. We constructed a principal component analysis (PCA)-based tool to guide immunophenotypic classification of B-CLPD. Three reference groups of immunophenotypic data files-B-cell chronic lymphocytic leukemias (B-CLL; n = 10), mantle cell (MCL; n = 10) and follicular lymphomas (FL; n = 10)--were built. Subsequently, each of the 175 cases studied was evaluated and assigned to either one of the three reference groups or to none of them (other B-CLPD). Most cases (89%) were correctly assigned to their corresponding WHO diagnostic group with overall positive and negative predictive values of 89 and 96%, respectively. The efficiency of the PCA-based approach was particularly high among typical B-CLL, MCL and FL vs other B-CLPD cases. In summary, PCA-guided immunophenotypic classification of B-CLPD is a promising tool for standardized interpretation of tumor IP, their classification into well-defined entities and comprehensive evaluation of antibody panels.

Figure 1

Illustrating example of the CLL vs MCL (a, d and g), CLL vs FL (b, e and h) and FL vs MCL (c, f and i) one vs one comparisons of flow cytometry data files corresponding to the three B-CLPD reference groups as classified by the PCA projections (first vs second principal components). The PCA based classification profile obtained for four cases tested is displayed: a typical CLL (brown dots), one FL (dark green dots), a MCL (dark blue dots) and a lymphoplasmacytic lymphoma (LPL; black dots). In a–f, each dot corresponds to a single cell event, whereas in panels g–h, mean principal component 1 vs principal component 2 values for each case (same PCA as in panels d–f, respectively), are shown.