Abstract
Particles possessing a density of 1.16 g/ml and encapsulating a 70S RNA and a RNA-instructed DNA polymerase (reverse transcriptase) have been prepared from the spleen of a patient with chronic lymphocytic leukemia. These particles have been converted to cores with a density of 1.26 g/ml and containing the enzyme-RNA complex, in complete analogy to the known RNA tumor viruses of avian and murine origin. The reverse transcriptase was purified from the cores by column chromatography to a stage showing a single major protein band of 70,000 daltons in a gel electrophoresis. The enzyme was capable of transcribing heteropolymeric RNA into DNA complements as demonstrated by specific back hybridization to template RNA. The leukemic spleen would appear to represent an important source of this enzyme, as well as other potentially important leukemia-specific reagents.