Histochemical Demonstration of Diaphorases and Dehydrogenases in Normal Human Leukocytes and Platelets

A method for the cytochemical demonstration of oxidative enzyme activity in the white cells and platelets of peripheral blood is described. The technic depends upon the reduction of a colorless ditetrazolium salt to a blue granular insoluble diformazan at the site of enzyme activity. Identification of the cells is accomplished by phase microscopy thus avoiding the deleterious effects of fixation and counterstaining. The distribution of oxidative enzyme activity in normal peripheral blood as observed by this method is discussed.