The Histochemical Study of Zinc Content in Granulocytes in Normal Adults and in Hematologic Disorders

By ST u’ iIsLAw SZMIGIELSKI AND JOANNA Ln’w T HE PHYSIOLOGIC and biochemical role of zinc (Zn), as a cofactor of many important enzymes ( carboxypeptidase, dehydrogenases, alkaline phosphate, carboanhydrase) is now well established, but our present knowledge of zinc metabolism and transport in the human body is still incomplete. Vallee1 estimated Zn content in whole blood at 880 gamma/100 ml. He also showed the existence of an exchange of Zn between the plasma proteins ( containing 12 per cent of whole blood Zn ) and the Zn compounds in erythrocytes and leukocytes ( accounting for about 85 per cent and 3 per cent of whole blood Zn, respectively ) . The individual granulocytes, especially eosinophihic or basophilic, are relatively rich in Zn ( 14.2 gamma of Zn per 10 cells)2 and probably contains more Zn than does any other cell in the body. A protein containing 0.3 per cent of Zn, accounting for about 80 per cent of the granulocyte’s Zn, has been extracted from normal leukocytes by Hoch and Vallee.3’4 This Zn containing protein is probably an enzyme, but the nature of its enzymic activity is still unknown. It has no carboanhydrase activity.4 Gibson and Vallee5 reported decreased values of Zn in leukemic leukocytes and Dennes and Tupper2’0 found most leukemic cells contained approximately only half the amount of Zn found in normal leukocytes separated from blood by the use of dextran technic. The difference was statistically significant. The histochemical demonstration of Zn in blood and bone marrow smears was performed by Mager and McNary.7’5 These investigators described a method for histochemical detection of Zn in blood cells and discovered decreased amounts of Zn in leukemic granulocytes. Quantitative estimations, however, were not done.