About the possible origin and mechanism of circulating DNA - Apoptosis andactive DNA release

Background: In addition to cell lysis, apoptosis has been advanced as the o rigin of circulating DNA on the basis of several observations. Plasma or se rum DNA often presents a ladder pattern reminiscent of that displayed by ap optotic cells when subjected to electrophoresis. However, the phenomenon of active release of DNA from cells might also be expected to result in a lad der pattern on electrophoresis. Non-dividing cells, such as lymphocytes, fr og auricles and cultured cell lines including HL-60, spontaneously release a nucleoprotein complex within a homeostatic system in which newly synthesi zed DNA is preferentially released. Conclusion: In relation to DNA synthesi s, the phenomenon of extracellular DNA in different culture conditions favo rs apoptosis or spontaneous active DNA release. (C) 2001 Published by Elsev ier Science B.V.