Histochemical Demonstration of Reducing Activity in Normal and Leukemic Blood and Bone Marrow Cells.

Summary Reducing activity in blood and bone marrow cells can be demonstrated with the aid of pp′ diphenylene bis 2-(3,5 diphenyl tetrazolium chloride). Under the microscope, sites of reduction are indicated by small purplish granules due to the formation of insoluble formazan. A positive reaction is seen in the myeloid elements with the exception of the myeloblasts. Lymphocytes and monocytes show a varying degree of activity. Nucleated red cells and megakaryocytes are occasionally positive. In leukemic blood, myeloblasts are consistently negative while the more mature elements show reducing activity.