Enzyme cytochemistry of blood and marrow cells.

Diseases of the blood and bone marrow are commonly associated with abnormalities of oxido-reductase and lysosomal enzymes within individual erythrocytes and leucocytes. There are considerable technical difficulties, however, in adapting enzyme histochemical techniques to the study of haemopoietic tissue since individual cells are readily disrupted during processing, show variable enzyme activity according to the stage of maturation, and possess a lipoprotein cytoplasmic membrane which hinders reagent penetration. Cytochemical techniques for the study of oxido-reductase systems are of importance in the study of the neutrophil in infected patients, the erythrocyte in glucose-6-phosphate dehydrogenase deficiency, and the primitive blast cell in acute leukaemia. Lysosomal enzymes are of importance in the study of the neutrophil in infected patients and in the differential diagnosis of acute leukaemia. Some examples of recent studies of these enzyme systems are given to illustrate technical procedures involving cytocentrifugation of cells on to glass slides, adjustment of the osmolality of the reaction mixture, and the study of smeared cells as opposed to cells incubated in suspension.