Journal of Experimental Medicine, Vol 143, 1249-1264, Copyright © 1976 by Rockefeller University Press
Characterization of DNA excreted from phytohemagglutinin-stimulated lymphocytes
JC Rogers
The DNA released into the culture medium after phytohemagglutinin (PHA)
stimulation of human peripheral blood lymphocytes has been purified and
characterized. It is double stranded, sediments at 7-8S in alkaline
sucrose, and has a Tm determined optically and by thermal elution from
hydroxyapatite that is substantially lower than that found for lymphocyte
cell DNA. Media DNA contains a major component reassociating with an
average Cot-1/2 of 87 mol X s/liter, compared to a Cot-1/2 of 770 mol X
s/liter for the unique fraction of cell DNA as measured by reassociation in
0.6 M Na+. This component of media DNA consists of unique sequence elements
which are largely shared in media DNA preparations from cultures derived
from different cell donors. The marked difference between media DNA and
cell DNA indicates that media DNA is not derived from cell death and lysis,
rather than some unique portion of lymphocyte DNA is apparently excreted
from the cells during PHA-stimulated growth.