Nicotinamide adenine dinucleotide-linked dehydrogenases, SDH, NADH and NADPH diaphorases were assayed with cytochemical methods in white blood cells in bone marrow cells using tetrazolium salts, Nitro-BT and MTT. In unfixed smears specific enzymatic activity was demonstrated for glucose-6-phosphate dehydrogenase, succinic dehydrogenase and NADH diaphorase. In fixed smears the activity of lactic dehydrogenase and succinic dehydrogenase was shown. The action of NADH and NADPH diaphorases was demonstrated in the fixed smears only in the presence of NADH and NADPH. Supravital methods are inadequate for demonstration of specific enzymatic activity.
Lactic dehydrogenase activity in cells was estimated in a semiquantitative way. The enzymatic action of the dehydrogenases and the diaphorases was stronger in younger cells and decreased progressively with their maturation.