Diagnosis of acute myeloid leukaemia with the use of monoclonal anti-neutrophil elastase (NP57) reactive with routinely processed biopsy samples.

The reactivity of a monoclonal anti-neutrophil elastase antibody (NP57) with routinely processed biopsy samples from various acute leukaemias has been examined and compared with that of chloroacetate esterase and CD15 (hapten X), two other myeloid cell-associated markers detectable in paraffin sections. No staining was seen with these markers in 14 cases of acute lymphoblastic leukaemia. In contrast the neoplastic cells in 27 of 37 acute myeloid leukaemias were NP57 positive. Twenty of these were also positive for chloroacetate esterase, whereas CD15 was expressed in only six cases. These results indicate that detection of elastase with monoclonal NP57 forms a useful supplement to traditional methods for the histopathological diagnosis of acute myeloid leukaemias.