Routine immunophenotyping of acute leukaemias.

Recent progress in immunophenotyping includes the availability of monoclonal antibodies (MAbs), knowledge of specificity and reactivity patterns of these reagents, and the technical improvements and standardization of immunofluorescence and immunocytology staining procedures, including flow cytometry. These advances have contributed significantly to the establishment of immunophenotyping as an essential diagnostic tool in the differential diagnosis of types of acute leukaemia. Immunophenotyping allows for the objective and reproducible distinction of acute lymphoblastic leukaemia (ALL) from acute myeloblastic leukaemia (AML) and of T-lineage from B-lineage ALL. Immunologically defined ALL and AML subtypes have been found to convey prognostic significance. Using cell lineage-specific and differentiation stage-specific MAbs, cases of T- and B-lineage ALL and of AML can be further classified into a number of different subtypes. Routine immunophenotyping concentrates on the diagnostic enquiry into a few major, clinically relevant subtypes; only a limited number of crucial reagents are employed that are commercially available. The simplification and standardization of discriminatory immunomarker panels make immunophenotyping a reliable diagnostic instrument for the provision of critical data to make a differential diagnosis. An effort to identify the nature and origin of the blast cells precisely, immunological typing definitely plays an important part in the multiple-marker analysis of acute leukaemia (morphology, cytochemistry, karyotyping, genotyping) for applied diagnostic and fundamental research purposes.