THE EFFECTS OF AGING ON THE FUNCTION OF ALVEOLAR MACROPHAGES IN MICE

In order to determine whether the function of alveolar macrophages (AM ) is modulated by aging, we measured the TNF-alpha production, phagocy tic function, and surface antigen expression of AM from young and old mice. When AM were primed by IFN-gamma (500 units/ml) and triggered by LPS (100 mug/ml), TNF-alpha production by AM was significantly smalle r in old mice as compared with young mice (young mice: 161.7 +/- 28.2 units/ml; old mice: 89.3 +/- 13.6 units/ml, P < 0.05). The percentage of AM which phagocytosed latex particles (more than one particle) in o ld mice was significantly lower than in young mice (young: 78.1 +/- 2. 5%; old: 62.8 +/- 3.4%, P < 0.05). Ia antigen expression of the AM was significantly higher and asialo-GM1 antigen expression was significan tly lower in old mice than in young mice (Ia: young, 0.030 +/- 0.005; old, 0.092 +/- 0.024, P < 0.05; asialo-GM1: young, 0.97 +/- 0.01; old, 0.75 +/- 0.07, P < 0.01). These results suggest that alveolar macroph age function is at least decreased in part with aging in mice.