The relationship of age, strain and species to the reducing activity of leukocytes.

By ALBINA ANN YAKAITIS G RANULES of formazan resulting from tile reduction of neotetrazolium have been observed in leukocytes by Wachstein) Studies were made on rats, mice, guinea pigs, rabbits and on normal and leukemic humans. In normal human material, formazan formation was noted principally in the mature myeloid elements and in varying degrees in lymphocytes and monocytes. In myelocytic leukemia, mature myeloid cells reduced neotetrazolium, but immature cells were negative in thlis regard. In chronic iymphocytic leukemia, most of the cells of the polymorphonuclear series and varying percentages of the lymphocytes were positive. For the present study, 2( p-iodophenyl)-3-( p-nitrophenyl)-5-phenyltetrazohum chloride ( INT ) was used because of its rapid reduction and its large crystal formation . Altilongil these crystals preclude precise intracellular localization, they serve as convenient markers for “counting” positive cells. Thus a semi-quantitative measure of enzyme activity may be made.