Induction of superoxide dismutase in leukocytes by paraquat: correlation
with age and possible predictor of longevity
Y Niwa, K Ishimoto and T Kanoh
Niwa Institute for Immunology, Kochi-ken, Japan.
Reactive oxygen species (ROS) are thought to play a role in the aging
process as well as in a number of human diseases states. Superoxide
dismutase (SOD), an enzyme that scavenges the superoxide anion (O2-) is
constitutively expressed in leukocytes and other tissues. When assayed in
peripheral blood leukocytes (PBL), constitutive SOD activity shows little
variation among individuals of different ages. We have found that
significant induction of SOD activity occurs in PBL incubated in vitro with
paraquat, an agent known to cause intracellular O2- production. This
induction was found to be highly age dependent; lymphocytes from 36 healthy
subjects aged 20 to 40 years showed an increase of 85% +/- 10%, versus an
increase of only 8% +/- 1% for lymphocytes from 30 healthy subjects aged 65
to 79 years (P less than 10(-4)). Forty subjects, aged 67 to 73 years, who
were healthy at the time of assay of leukocyte SOD induction were followed
up 5 years later. Nineteen of these subjects had died; all 19 had shown SOD
induction of less than 10% (range, 0% to 7%; mean, 2.4%). In contrast, of
the 21 survivors (range, 2.5% to 50%; mean, 21%), 12 had shown SOD
induction greater than 10%, and 7 had shown SOD induction greater than or
equal to 35% (P less than 10(-3)). Thirteen of the 19 deaths were
attributable to malignancy or cerebrocardiovascular disease. Preservation
of leukocyte SOD inducibility appears to correlate with longevity in
elderly individuals and may be of value in predicting resistance to
malignancy or fetal cardiovascular events.
Volume 76,
Issue 4,
pp. 835-841,
08/15/1990
Copyright © 1990 by The American Society of Hematology
