Detection of myeloperoxidase activity in primary leukemic cells by an enhanced chemiluminescent assay for differentiation between acute lymphoblastic and non-lymphoblastic leukemia.

Background: Myeloperoxidase (MPO) plays a crucial role in the differentiation of acute lymphoblastic leukemia (ALL) and acute non-lymphoblastic leukemia (ANLL). In this report, we proposed the application of the enhanced chemiluminescent (ECL) technique to the determination of MPO activity in blasts of acute leukemia (AL).
Methods: Bone-marrow samples were obtained from 23 patients with AL (ALL, 5 cases; ANLL, 13 cases; AUL, 1 cases; mixed-lineage AL, 4 cases). Cells were incubated with a standard reaction mixture and chemiluminescence was measured. The mean peak light emission (PLE) was assessed.
Results: When the cut-off point of PLE was settled at 2483, which was set for the discrimination between ANLL and ALL (mean + 3 x SD of ALL samples, n=5), all cases of ALL were MPO-negative, and ten of the thirteen ANLL patients were MPO-positive, which was concordant with cytochemical staining. In addition, this technique was able to demonstrate MPO activity in 4 mixed-lineage AL cases which did not stain for MPO in cytochemistry preparations.
Conclusions: Our ECL technique is simple, inexpensive, and easier to perform compared to other procedures used to measure MPO activity in AL.