Monocyte analysis in chronic myelomonocytic leukaemia.

It is suggested that monocytes in patients with chronic myelomonocytic leukaemia (CMML) or chronic myeloid leukaemia (CML) with monocytosis have morphological/functional abnormalities which cause inaccurate counting in automated analysers. In this study, monocytes in 21 normal and 14 CMML blood samples were subjected to morphological analysis and were counted by the manual reference method, three automated analysers and esterase staining. Morphological analysis showed no significant difference between control and CMML monocytes. The alpha-naphthyl acetate esterase scores, a measure of monocyte function, showed a reduction of 40% in CMML monocytes compared to controls. Counts by analysers showed that the Sysmex NE 8000 was the least accurate for CMML monocyte counts and that the Coulter STK-S and Sysmex SE 9000 gave results closer to the manually counted standards.