Abstract

Samples from 49 cases of myeloproliferative diseases were tested by an immunocytochemical technique for leucocyte lysozyme and lactoferrin. The presence of these constituents in myeloid precursors from cases of acute and chronic myeloid leukaemia reflected the degree of cellular maturation, lysozyme appearing (as it does in normal myeloid cells) at the stage of primary granule production (in promyelocytes), while lactoferrin wad detectable only in more mature, secondary granule-containing myeloid cells. Auer rods stained positively for lysozyme, in keeping with their relationship to primary granules. Monocytes from five cases of leukaemia showing predominantly monocytic differentiation were indistinguishable from normal monocytes in their staining reactions for lysozyme despite the presence of raised serum and urinary lysozyme levels. In four cases of acute myeloid leukaemia circulating polymorphs deficient in lactoferrin were detected: in one of these cases a similar percentage of polymorphs was lysozyme negative.