Immunophenotyping of Adult Acute Leukemia by Immuno-Alkaline Phosphatase Labeling

The French-American-British (FAB) classification system has provided a popular classification for acute leukemias based on cell morphology and cytochemistry [1]. However, difficulties with some diagnostic criteria are evident. The major difficulties include distinguishing Ml from L2 in cases where peroxidase staining is negative [10]. Immunophenotyping using fluorescence microscopy or flow cytometry has emerged as an essential tool for the categorization of acute leukemias. A number of more recent papers have described the use of immunocytochemical labeling employing the alkaline phosphatase/anti-alkaline phosphatase (APAAP) method and light microscopy [4,6,9,16]. Immunocytochemistry has some advantages: simultaneous staining for immunoprofile and morphology, small sample quantity, enhanced sensitivity, long-term storage, and no expensive instrumentation. In this paper we describe the diagnostic value of the APAAP technique in 61 consecutive patients with acute leukemia.