LIGHT SCATTER CHARACTERISTICS OF BLAST CELLS IN ACUTE MYELOID-LEUKEMIA - ASSOCIATION WITH MORPHOLOGY AND IMMUNOPHENOTYPE

Aims-To analyse the forward scatter/side scatter (FSC/SSC) distributio n of acute myeloblastic leukaemia (AML) blast cells in order to assess whether it correlates with their morphology, immunophenotype, and cli nical and biological disease characteristics. Methods-FSC/SSC patterns were established upon taking into account the localisation of the res idual T lymphocytes in the FSC/SSC dot plot as an internal biological standard. One hundred and seventy one newly diagnosed AML patients wer e analysed and five different FSC/SSC patterns were established. These five patterns could be grouped into two major categories taking into account the FSC/SSC distribution of normal cells in a bone marrow aspi rate: immature patterns (1 and 2) and mature patterns (3, 4, and 5). T hese FSC/SSC patterns were correlated with and biological characterist ics patients. Results-No significant associations were detected in rel ation to the clinical and haematological disease characteristics and t he prognosis of these patients. By contrast there was a significant co rrelation between the FSC/SSC pattern of the AML blast cells and the F AB classification. An increased reactivity for the antigens associated with myeloid differentiation such as CD13, CD33, CD11b, CD15, CD14, C D4, CD56, and/or CD16 was detected among cases showing a mature FSC/SS C pattern (3, 4, and 5), both in the whole series and even within each of the FAB AML subtypes. By contrast, the reactivity for the CD34 pre cursor cell associated antigen was higher among those cases displaying an immature FSC/SSC pattern, this being observed even within each FAB subgroup. Conclusions-The FSC/SSC pattern distribution of AML blast c ells not only provides an additional objective and reproductible syste m for the classification of these leukaemias but it may also represent a connection between the FAB morphological groups and the immunopheno typic classification of AML patients.