CD9 expression can be used to predict childhood TEL/AML1-positive acute lymphoblastic leukemia: proposal for an accelerated diagnostic flowchart.

CD9 has been shown to be differentially expressed in childhood TEL/AML1-positive acute lymphoblastic leukemia (ALL). We confirmed this finding in large Affymetrix data sets and in 80 new cases at both RNA and protein levels. Moreover, we showed that mean fluorescence intensity of CD9 by flow cytometry can distinguish TEL/AML1-positive ALL from other BCP-ALL. Using ROC analysis, the most efficient model for predicting TEL/AML1-positive ALL combined CD9 (mean fluorescence intensity <or=20) and CD10 values (positive cells >40%). Finally, we propose a faster procedure for optimizing the diagnosis of childhood BCP-ALL subgroups.