Improved technology for the bioenergetic profiling of human blood cells enables population-based screening for alterations in mitochondrial respiration. Mitochondria are sensitive to oxidative stress, and the aim of this study was to quantify mitochondrial respiration in freshly isolated lymphocytes and monocytes challenged with a bolus of H2O2. Mitochondrial reserve capacity, calculated as the difference between basal oxygen consumption and maximal activity after uncoupling of the electron transport chain, was the most sensitive to H2O2. Treatment of lymphocytes with 20 μM H2O2 reduced the reserve capacity by approximately 50%, while monocyte reserve capacity was five times more resistant. Healthy donors of a similar age were tested to determine the variation between individuals, and within the same individuals tested on several different occasions. Lymphocytes obtained from a population of people aged 70-80 years showed a similar inhibition upon challenge with H2O2 as those aged 18-25 years, indicating no decline in resilience with age.
Keywords: Oxidative stress; ageing; bioenergetics; hydrogen peroxide; mitochondrial respiration.