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Age-related decrease in accessory cell function of human alveolar macrophages
G Zissel1, M Schlaak, J Müller-Quernheim
1Research Centre Borstel, Medical Hospital, Borstel, FRG.
Background:
Suboptimal function of an aged immune system may significantly contribute to morbidity and mortality in the elderly. In contrast to lymphocytes, only little is known about changes of cells from the monocyte/macrophage lineage. Especially the changes of their accessory function, which are necessary for optimal T cell stimulation are controversially discussed.
Methods:
We measured the accessory function of monocytes (PBM) and alveolar macrophages (AM) and correlated their accessory function with the age of the patients.
Results:
We found a significant decrease in accessory function of AM with the age (rs = -0.5, P < 0.006) but not of PBM (rs = -0.4, P > 0.1). Additionally, we found a significant decrease in the percentage of AM (rs = 0.3, P < 0.005) and an increase in the percentage of lymphocytes (rs = 0.3, P < 0.02) in the bronchoalveolar lavage. No correlations could be found with other lavage parameters or with unstimulated in vitro TNF-alpha, TGF-beta, and IL-6 release of bronchoalveolar lavage cells; however, in stimulated BAL-cell cultures we found a weak but significant correlation between TNF-alpha release and the age (rs = -0.3, P < 0.02).
Conclusions:
Impairment of accessory cell function of alveolar macrophages may contribute to an increased risk of pulmonary infection of elderly persons.