Clinical value of the quantitative expression of the three epitopes of CD34 in 300 cases of acute myeloid leukemia

Service d'Hematologie biologique, CHU de Dijon, 2 Boulevard Marechal de Lattre de Tassigny, 21034 Dijon Cedex, France. mmaynadie@chu-dijon.fr BACKGROUND AND OBJECTIVES: The various epitopes of the CD34 molecule have been classified according to their different sensitivities to enzymatic cleavage by neuraminidase, chymopapain and a glycoprotease from Pasteurella haemolytica. Although monoclonal antibodies have been developed that specifically identify these epitopes, few studies have evaluated the distribution and quantitative expression of such epitopes on leukemic blasts. DESIGN AND METHODS: We report here a prospective multicenter study in which we examined and quantified the expression of the 3 classes of CD34 on fresh leukemic blast cells from 300 cases of acute myeloid leukemia (AML). The binding of monoclonal antibodies was studied by flow cytometry, allowing evaluation of blast cell positivity as well as their mean fluorescence intensity. These quantitative data were made comparable between centers by means of a calibration curve established with the same reagents in all laboratories. RESULTS: Quantitative expression of class I epitope was significantly higher than that of class II and class III epitopes (p