Neutrophil migration, oxidative metabolism, and adhesion in elderly and young subjects

Objective: To evaluate neutrophil functions in the elderly. Methods: We investigated the PMN migration in vivo and PMN superoxide production and adhesion in response to a variety Of compounds; PMN have been isolated both from blood and from a skin experimental exudate (obtained by Senn's skin window technique) of 25 normal elderly and of 25 normal young control subjects. Results: No difference was found in PMN migration in vivo (62.9 +- 21.3 times 10-6 and 65.5 +- 9.1 times 10-6 PMN/cm-2/24 hours in elderly and young subjects respectively), neither were different the adhesion under basal condition and after some stimuli and the superoxide production in basal condition and in response to STZ and PMA in two groups. In elderly subjects superoxide production, in response to fMLP, markedly resulted lower than in young controls both by circulating PMNs (3.6 +- 2.7 and 9.3 +- 3.3 nMOLES O-2-/10-6 PMN respectively, p lt 0.0001) and by exudate PMNs (13.6 +- 4.3 and 19.4 +- 6 nMOLES O-2-/10-6 PMNs respectively, p lt 0.005). Conclusion: Many PMN functions in the elderly do not differ from young people, suggesting that the overall defense function of these cells is not affected by aging. The only parameter that we have found to be different between the two groups is the poor superoxide production after fMLP stimulus of PMNs. The stimulus- and function-specificity of this defect in PMNs from elderly subjects indicates the existence of a dysregulation of the signal transduction pathway distal to fMLP receptor and proximal to NADPH oxidase activation.