Ten healthy elderly volunteers (mean age: 78.9) underwent a battery of neutrophil function tests. Resting adherence to endothelium, random and directed migration, phagocytosis-induced chemiluminescence, and granule secretory behavior were all indistinguishable from young healthy controls. However, in vivo delivery of neutrophils into skin abrasions was significantly reduced: 8.4 X 10(5), versus 2.7 X 10(6) in the young. In addition, their neutrophils showed a smaller increase in the surface adhesion glycoprotein CD11 and in adherence to endothelium in response to stimulation with FMLP than did cells from young controls. Inversely, baseline CD11 expression was higher in elderly subjects, suggesting that their cells may have an in vivo defect in mediator responsiveness. Serum immunoglobulin and complement concentrations were also compared. The mean IgM level of 106.3 mg/dl in the elderly was significantly below the 154.4 mg/dl in the young. In contrast, concentrations of C3, C4, and total hemolytic complement were significantly higher in the elderly.