Histoenzymology of oxidases and dehydrogenases in peripheral blood lymphocytes and monocytes for the study of mitochondrial oxidative phosphorylation

Histoenzymological methods usually performed on muscle fibres have been ada pted to assess the functioning of oxidative phosphorylation in human circul ating blood lymphocytes and monocytes. Oxidases and dehydrogenases were ana lysed in lymphocyte/monocyte smears. The specificity of each histoenzymolog ical reaction was tested using a specific respiratory chain inhibitor: rote none for NADH diaphorase, thenoyltrifluoroacetone for succinate dehydrogena se, potassium cyanide for cytochrome c oxidase and oligomycin for ATPase. C omplex I activity was detected, but inhibition with rotenone was incomplete . Complexes II, IV and V were almost completely inhibited. These observatio ns indicate that histoenzymology is a valuable method for detecting the act ivity of these oxidative phosphorylation enzymes in lymphocytes and monocyt es. The histoenzymology tests performed on fresh peripheral blood cells res embled those used for muscle biopsies. They could be useful for the diagnos is of respiratory chain disorders in patients.