Studies on the Energy Metabolism of Human Leukocytes: I. Oxidative Phosphorylation by Human Leukocyte Mitochondria

1. Oxidative phosphorylation has been studied in mitochondrial preparationsfrom human leukocytes, using recently developed methods for homogenization,measuring respiration, and assaying for ATP.

2. Appreciable stimulation of both respiration and phosphorylation waslimited to 3 substrates: succinate, malate, and -glycerophosphate. The effectsof other substrates were minimal.

3. The stimulating effects of these 3 substrates responded to inhibitors in amanner typical of mitochondrial oxidative phosphorylation. There was alsoconsiderable endogenous activity which, however, was insensitive to inhibitors.It is concluded the endogenous respiration and phosphorylation are not associated with electron transport. Subtracting their values from the data, P/Oratios consistent with good phosphorylation with the 3 substrates are obtained.

4. Studies with oligomycin and dinitrophenol suggest the presence ofrespiratory control. This indicates the mitochondria are intact. It is concludedthat in the intact leukocyte the mitochondria are a major source of ATP.

Submitted on December 16, 1966 Accepted on March 19, 1967