Acute leukaemia immunophenotyping in bone-marrow routine sections

Immunohistochemistry of acute leukaemias in bone-marrow paraffin sections i s commonly thought to be useless because of the poor preservation of many l ineage-related markers. The recent development of antibodies against fixati ve-resistant epitopes and of new antigen retrieval techniques, however has expanded the possibility of accurately testing routine samples. To assess t he relevance of paraffin section phenotyping in lineage determination, 110 examples of acute leukaemia were studied by specific antibodies against CD1 a, CD3, CD15, CD20, CD34, CD68, CD79a, TdT, myeloperoxidase, glycophorin A, and factor-VIII-related antigen. The cases included 59 acute myeloid leuka emias, classified according to the FAB cooperative group criteria, 39 precu rsor B-cell acute lymphoblastic leukaemias (Ws), seven T-ALLs, and ave mixe d precursor B-cell/myeloid acute leukaemias. The combination of the markers employed always allowed the identification of the cell lineage (myeloid, l ymphoid or mixed) and, in some instances, of phenotypic profiles characteri stic of distinct acute leukaemia subtypes, According to the results obtaine d, bone-marrow biopsy may be regarded as a reliable tool for acute leukaemi a diagnosis; this observation is of practical relevance especially for the classification of cases which lack circulating blasts in the peripheral blo od or showing dry tap at bone-marrow aspiration.