The automation of cytochemical methods for automated cytophotometers

The development of an automated differential white blood cell counter is reviewed. After the red cells have been lysed, the white cells are counted by staining and passing through an electro-optical chamber in liquid suspension, surrounded by a laminar, or sheath, stream. Staining procedures were made specific for each type of leukocyte, and separate channels were used for counting each type. Staining intensity and characteristics of the various types of blood cells are discussed. They relate to enzyme levels and the effect on differentiation and identification of the cells. Since reasons for some of the design features are not obvious, discussion of the relevant problems is included. Several applications that go beyond routine differential counting are described.