“…Alternatively, malignant cells in precursor B-ALL patients can be distinguished from normal early B-lineage cells based on atypical immunological characteristics. This concerns tumour-associated ectopic expression of antigens such as TdT, CD66c or NG2, crosslineage antigen expression, maturational asynchronous antigen expression, antigen overexpression or loss of markers expressed in normal B-cell precursors (Van Dongen et al, 1996;Dworzak et al, 1998b;Ciudad et al, 1999;Sugita et al, 1999). Such characteristics can be detected with currently available four-colour flow cytometry in at least 85% of the cases (Wells et al, 1998;Campana & CoustanSmith, 1999;Lucio et al, 1999;Weir et al, 1999).…”