Platelet activation is caused not by aging but by atherosclerosis

Platelet activation increases with age, although it is still controversial whether it derives from aging per se or from atherosclerosis concomitant with aging. The purpose of this study is to clarify the association between platelet activation and aging or atherosclerosis. We studied the ultrastructure of platelets in the elderly subjects with or without atherosclerosis and healthy young subjects. The platelet shape changes were evaluated by transmission electron microscopy and the contents of peroxidase and fibrinogen were assessed using a scoring system based on cytochemical staining and immunogold marking methods. No significant differences in platelet shape changes and the contents of peroxidase and fibrinogen in platelet were observed between healthy young and nonatherosclerotic elderly subjects, although the frequency of pseudopods increased and the content of peroxidase decreased in atherosclerotic elderly patients. It is suggested that platelet activation is not derived from aging but from atherosclerosis, although it is difficult to separate aging from coexisting atherosclerosis.