Ultrastructural localization of DNA in leukemic cells using osmium ammine B

In order to determine whether there were any differences in distribution of nuclear DNA between acute lymphocytic leukemia (ALL) and acute myelogenous leukemia (AML), the localization of DNA in blasts from the bone marrow or buffy coat of 30 patients with ALL and 30 patients with AML was examined ultrastructurally by staining with osmium ammine B. By the ultrastructural cytochemistry, DNA in ALL cells was clumped in the nuclei, while in AML cells, it was dispersed. DNA had accumulated around the nucleoli of some blasts, and flecks of DNA were observed in nucleoli of a majority of blasts. The perinucleolar and intranucleolar DNA distribution could be classified into four types. The types with abundant perinucleolar DNA were frequently observed in ALL blasts, while the majority of AML blasts showed scant perinucleolar DNA. The types with intranucleolar flecks of DNA were more prominent in leukemic cells than in normal immature leukocytes. In conclusion, the pattern of distribution of DNA in the nuclei of leukemic cells differs between ALL and AML.