INFLUENCE OF AGE ON THE RELEASE OF REACTIVE OXYGEN SPECIES BY PHAGOCYTES AS MEASURED BY A WHOLE-BLOOD CHEMILUMINESCENCE ASSAY

Polymorphonuclear and mononuclear phagocytes play an important role in host defense, but may also cause tissue injury through excessive infl ammation. Reactive oxygen species (ROS) are not only directly ore indi rectly involved in a wide variety of clinical disorders, such as ather osclerosis, reperfusion injury, pulmonary toxicity and cancer, but the y are also important in the aging process. This process is associated with increasing susceptibility to infection. In this study we investig ated the influence of age and sex on phagocyte activation by means of a whole blood chemiluminescence (CL) assay. Circulating phagocyte acti vity was measured in 55 healthy volunteers (24 females, 31 males) aged from 6 to 92 years. Using an automated luminescence system, phagocyte s were stimulated by polystyrene beads and Luminol-enhanced CL was det ermined in terms of peak height and peak time in freshly withdrawn, pe ripheral venous whole blood. An extremely significant positive correla tion (p < 0.0001) between the maximum of light emission after stimulat ion and increasing age was found. This finding is true for the total p opulation of blood phagocytes as well as for a single cell. In contras t the time of the appearance of the maximum of light emission showed a n extremely significant inverse correlation (p < 0.0003) with increasi ng age. The influence of sex on the CL-parameters showed no significan t difference between women and men. It is concluded that the increased susceptibility of circulating phagocytes to oxidative burst in elderl y subjects may be the consequence of several biological events. Senesc ent cells express more and also have new antigens on their surfaces th at trigger an autoimmune response. Cellular senescence appears earlier in old organisms. Therefore phagocytes in aging individuals may be in creasingly involved in their scavenger tasks that grow with the catabo lic bias in cell turnover. Moreover, atherosclerotic alterations in th e intima and endothelial lesions are physiologic concomitants of age a nd may lead to a stimulation of circulating phagocytes. Copyright (C) 1996 Elsevier Science Inc.