Immunophenotypic characterisation of monocytoid differentiation markers in acute non-lymphoblastic leukaemias.

The FAB classification of acute non-lymphoblastic leukaemias has been shown to have some clinical use in the prognostication of patient survival. ANLL with monocytoid features (M4, M5) fare worse than those which are predominantly myeloblastic (M1, M2). Classification is, however, sometimes difficult if non-specific esterase activity is not strongly expressed. Monoclonal antibody characterisation of myeloid differentiation antigens may be of some use as a supplementary aid. We immunophenotyped the blast cells from 26 cases for HLA-Dr, CD14 (Mo2, My4), CD13 (My17) and CD33 (My9) expression using the APAAP method. A combination of CD14 and CD33 used together was useful in differentiating myeloblastic from monocytoid acute non-lymphoblastic leukaemias. We conclude that the use of surface markers is a useful adjunct to the diagnostic means presently available.