Leukemic mitochondria. II. Acute monoblastic leukemia.

Qualitative and quantitative ultrastructural studies were performed on mitochondria of leukemic monoblasts from 15 patients with acute monoblastic leukemia. Similar comparative observations were made on mitochondria of myeloblasts from 14 hematologically normal controls. No significant quantitative differences were noted between normal and leukemic mitochondria. Area measurements were approximately equal. Qualitative differences between the two groups consisted of increased numbers of irregularly shaped mitochondria, damaged mitochondrial membranes, mitochondria with damaged matrix, and small granules in mitochondria in the leukemic group. Leukemic cells exhibited nuclear-mitochondrial contact and virus-like particles within damaged mitochondria. To confirm the presence of virus-like particles and to aid in our understanding of nuclear-mitochondrial interaction, a C-type virus producer MSV-MLV infected rat embryo cell culture was used for additional analysis. Mitochondrial abnormalities and increased frequency of virus in damaged mitochondria, often attached to mitochondrial membranes, were noted. Several lysosomes exhibited accumulations of virus and budding into lysosomes from lysosomal membranes. Mitochondria are important organelles in glycolytic-oxidative phosphorylation pathways, and carry extranuclear genetic information. Further studies of morphologic and biochemical abnormalities of leukemic mitochondria and the interaction between the mitochondria and the nuclei in leukemic cells are needed to provide researchers with data on extranuclear factors operating in oncogenesis.