Localization of DNA in ultrascopic nuclear appendages of polymorphonuclear white blood cells from patients with low serum B(12).

Polymorphonuclear white blood cells from patients with low serum vitamin B(12) (cobalamin) have ultrascopic appendages that project from their nuclear membranes. These appendages are most often found in the shape of blebs and stalks. Cytoplasmic rings that may be separated from the nucleus have also been seen. There is no known function for these appendages. Blood from 11 patients with low serum B(12) was processed for electron microscopic examination. In situ end-labeling of DNA and subsequent electron microscopic examination were performed. DNA was localized in all of the visualized appendages and rings. Treatment with DNases I and II decreased the labeling of these appendages by 63%. These DNA-laden appendages are a unique ultrastructural finding and may function to transfer fragmented DNA, which occurs in vitamin B(12) deficiency, from the nucleus into the cytoplasm.