Myeloperoxidase cytochemistry using 2, 7-fluorenediamine.

The myeloperoxidase cytochemical reaction has been well established as a valuable tool in the characterisation of various types of leucocytes. This method helps in the distinction between acute myeloid leukaemias (AML) and acute lymphoblastic leukaemias (ALL) as suggested in the French, American, and British (FAB) classification (Bennett et al., 1976). The most common substrates used are benzidine derivatives (Graham, 1918; Goodpasture, 1919). We have been using benzidine dihydrochloride (BDC) according to Kaplow's (1965) technique. However, the known carcinogenic potential of these substrates has led to the widespread removal of these reagents for clinical use in the United States, United Kingdom, and Japan. Inagaki et al. (1976) reported the use of the diamine derivative of fluorene: 2,7-fluorenediamine (2,7-FDA) as a good substitute of benzidine for the demonstration of myeloperoxidase in peripheral blood and bone marrow samples. We have compared qualitatively and quantitatively both reactions in order to assess objectively the usefulness of the new reagent.