Exposure to gamma-irradiation increases phorbol myristate acetate- induced
H2O2 production in human macrophages
EK Gallin and SW Green
Cell number, protein, and phorbol myristate acetate (PMA)-induced H2O2
production were measured in cultured human peripheral blood monocytes for
six days after exposure to varying doses of gamma-radiation. Both the
number of adherent cells and the protein per dish decreased with increasing
radiation doses. The dose of radiation decreasing the number of adherent
cells by 37% on days 4 and 6 postirradiation was 29 Gy. Four hours
postirradiation there was a small decrease in PMA-induced H2O2 production
for doses of 7.5 Gy or greater; levels returned to normal by eight hours
and increased at 24 hours postirradiation. By day 4 postirradiation
significant increases in PMA-induced H2O2 production were noted at all
radiation doses (2.5 to 50 Gy). This increase was not due to a shift in the
PMA dose-response curve, a change in the time course of the PMA response,
or an effect of decreased cell density on the assay system. Superoxide
levels were not significantly changed in cells exposed to 20 Gy. Catalase,
glutathione peroxidase, and superoxide dismutase levels also were
unchanged. Culturing irradiated cells with gamma-interferon increased
PMA-induced H2O2 release, which indicated that irradiated cells retained
their capacity to respond to gamma-interferon. These data demonstrate that
irradiation affects the PMA-induced H2O2 production of human monocytes in a
time- and dose- dependent manner. An increase in the release of reactive
oxygen intermediates by the macrophage may play a role in enhancing the
deleterious effects of radiation in vivo.
Volume 70,
Issue 3,
pp. 694-701,
09/01/1987
Copyright © 1987 by The American Society of Hematology
