DNA of free and complexed origin in human plasma: concentration and length distribution.

The DNA content in plasma of five healthy human individuals has been estimated. Structures ascertained by electron microscopy have been identified as double-stranded DNA. Depending on the isolation procedure applied the DNA molecules found may originate from free and/or complexed forms of DNA. The lengths range from less than 0.2 microns up to about 13 microns. DNA concentration is in the range of 3 to 11 ng/ml.