Staining of leukocytes by the tetrazolium method: correlation of results with the leukocyte count and with the clinical classification.

By PETER M. MARCUSE AND JOAN COCHRAN M ANY CYTOCHEMICAL methods have been used in hematologic studies. As applied to leukocytes, these include the demonstration of phosphatase activity,’ the visualization of phosphorylase,2 and the staining of intracytoplasmic glycogen.3 Intracellular visualization of dehydrogenase activity in leukocytes can be achieved by the use of the tetrazolium salts, which are reduced to colored, water-insoluble formazans. \Vachstein4 used the tetrazolium method to visualize the reducing activity in blood cells and in the bone marrow under normal conditions as well as in leukemia. Additional observations on the reduction of tetrazolium by leukocytes were recorded by Vercauteren.5 Bajuz and Szirmai6 used triphenyltetrazolium chloride solutions for the vital staining of leukocytes in peritoneal exudates of experimental animals. The following account deals with the technical details of the tetrazolium method as applied to laboratory studies and also with the significance of the results obtamed by this procedure. In addition to a basic method, a number of modifications were employed.