Respiratory and Calcium Transport Functions of Mitochondria Isolated from Normal and Transformed Human Lymphocytes¹

Methods have been developed to isolate mitochondria from small amounts of normal and leukemic human lymphocytes obtained from small volumes of circulating blood. Mitochondrial respiratory functions were measured by polarographic techniques, and active calcium uptake was measured by a spectrophotometric procedure utilizing the calcium-sensitive dye murexide. The results indicate that the rates of active oxygen consumption of normal human lymphocyte mitochondria are very low in comparison to values obtained from a number of animal tissue sources. Mitochondria extracted from the lymphocytes of leukemic patients and from cultured, and phytohemagglutinin-transformed human lymphocytes exhibited higher respiratory rates than did normal controls. Although respiratory rates were relatively low in all preparations, the efficiency of energy coupling (ADP:O, ratio of nmol of adenosine diphosphate phosphorylated to nanoatoms of O₂ consumed) was within normal limits. The mitochondria extracted from leukemic, cultured, and phytohemagglutinin-transformed lymphocytes exhibited high rates of respiratory substrate-supported calcium uptake compared to controls.