Cell-free plasma DNA: a marker for apoptosis during hemodialysis.
BACKGROUND
We evaluated whether cell-free plasma DNA might be an appropriate marker for cell damage during hemodialysis (HD) and whether it correlated with annexin V expression and 7-amino-actinomycin D (7AAD) nuclear staining of blood leukocytes.


METHODS
Circulating DNA, annexin V, and 7AAD were measured in HD patients before HD, 20 min after start of HD, and after HD had ended. Healthy volunteers provided control measurements. Necrosis and apoptosis were monitored by gel electrophoresis.


RESULTS
Plasma DNA concentrations were not significantly different between controls and patients before HD. Circulating DNA increased significantly (P < 0.05) after 20 min of treatment with HD. Post-HD concentrations of DNA were significantly higher compared with pre-HD and controls (P < 0.005). Agarose gel electrophoresis showed ladders typical of apoptosis in post-HD samples. Two subpopulations of CD45+ leukocytes were defined by flow cytometry: annexin V+/7AAD+ population for apoptosis, and annexin V+/7AAD- for early apoptosis. Compared with healthy controls, mean fluorescence (MF) of 7AAD+ apoptotic cells in the annexin V+/7AAD+ subpopulation before HD was not significantly increased. HD increased MF of 7AAD+ cells in the annexin V+/7AAD+ subpopulation. In this subpopulation, MF of annexin V+ cells was significantly higher (P < 0.01). MF of annexin V+ cells in the annexin V+/7AAD+ subpopulation increased during HD.


CONCLUSIONS
During HD, cell-free plasma DNA concentrations, annexin V expression, and 7AAD uptake in leukocytes increases. The increase in plasma DNA, appearing as ladders typical of apoptosis, and the 7AAD uptake in leukocytes demonstrate that the predominant portion of circulating DNA in HD patients originates from apoptotic leukocytes.
Atamaniuk
Johanna
J
Institute of Laboratory Diagnostics, Kaiser Franz Josef Hospital, Vienna, Austria. johanna.atamaniuk@wienkav.at
Ruzicka
Katharina
K
Stuhlmeier
Karl M
KM
Karimi
Alireza
A
Eigner
Manfred
M
Mueller
Mathias M
MM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017304:Annexin A5 / Q000097:blood*; D017209:Apoptosis; D015415:Biomarkers / Q000097:blood; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000097:blood*; D003609:Dactinomycin / Q000031:analogs & derivatives; D005456:Fluorescent Dyes; D006801:Humans; D007962:Leukocytes / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D009336:Necrosis; D006435:Renal Dialysis
D017304:Annexin A5; D015415:Biomarkers; D005456:Fluorescent Dyes; D003609:Dactinomycin; C025942:7-aminoactinomycin D; D004247:DNA