Protein expression profiling of acute lymphoblastic leukemia subclasses.

Parallel to fingerprinting of leukemia subclasses by gene expression profiling we propose to fingerprint leukemia subclasses using protein expression data collected by quantitative flow cytometry. A number of acute lymphoblastic leukemia subclasses with characteristic chromosomal aberrations (MLL; Bcr/Abl;E2A/PBX;TEL/AML1;hyperdiploid) have a unique gene expression profile as demonstrated by microarray studies (1-2). Among genes differentially expressed between leukemia subtypes are known proteins of which expression can be measured by quantitative flow cytometry using monoclonal antibodies (3). Here, univariate t-tests and multivariate principal component analysis (PCA) have been applied to profile phenotypes of 145 pB-ALL samples using expression data of 16 proteins. Expression of each marker protein has been quantified in terms of soluble fluorochrome (MESF) and coefficient of variation (CV). Materials:Patients material: A retrospective analysis has been performed on a total of 145 children diagnosed as suffering from precursor-B acute lymphoblastic leukemia (pB-ALL). We included 46 patients that were diagnosed for a MLL rearrangement between May 1995 and June 2001. As a control group representative of pB-ALL’s negative for MLL, we randomly selected 99 consecutively diagnosed patients from our MLL negative reference database.Among MLL patients, 26 are infants (aged < 1 year at diagnosis) and 20 non-infants while in the control group 5 infants (aged < 1 year at diagnosis) and 94 non-infants patients are present.