Assessment of monocytic component in acute myelomonocytic and monocytic/monoblastic leukemias by a chemiluminescent assay

Classically, the monocytic component of acute myelomonocytic (FAB-M4) and acute monocytic/monoblastic (FAB-M5) leukemias is demonstrated by nonspecific esterase positivity in cytochemical stainings. We have previously demonstrated that non-specific esterases from normal monocytes can be determined by a chemiluminescent method. In the present study, we investigated whether this assay can also determine the monocytic component of FAB-M4 and FAB-M5 and distinguish these acute myeloid leukemia (AML) categories. Bone marrow samples were obtained from 66 patients with AML (M0, two cases; M1, 12 cases; M2, 13 cases; M3, 10 cases; M4, 11 cases; M5, 12 cases; M6, two cases; M7, four cases). Cells were incubated with a standard reaction mixture and chemiluminescence was measured for 10 min. Two parameters were assessed, the peak (PLE) and the integrated light emission (ILE). Both PLE and ILE were higher in FAB-M4 and FAB-M5 subtypes compared to other AML subtypes (P