Neutrophils and low-grade inflammation in the seemingly normal aging human lung.

Lung function deteriorates with age and is associated with elastin loss, loss of elastic recoil and decline in diffusing capacity for carbon monoxide. To determine whether increased numbers of neutrophils can be found in the lower respiratory tract in healthy, clinically normal individuals who are more advanced in age, we performed bronchoalveolar lavage (BAL) on individuals in three discontinuous age groups (Group I, 19-36 years; Group II, 45-55 years; Group III, 64 83 years). We found that neutrophils were increased in many individuals in Group III compared to Group I. The neutrophil cell differential count was 1.44+/-0.18% (mean+/-S.E.M.) for Group I versus 3.88+/-0.81% for Group III (P < 0.01) and neutrophils x 10(3)/ml BAL fluid was 1.7+/-0.2 versus 7.2+/-1.7 for Group I versus Group III, respectively (P < 0.01). Similarly, interleukin-8 (IL-8) (8.5+/-1.7 vs 36.8+/-9.4 pg/ml, P < 0.01) and neutrophil elastase (NE) complexed to alpha1-antiprotease (1.2+/-0.1 vs 16.6+/-7.1 ng/ml, P < 0.02) were significantly elevated in the oldest versus youngest age group, although alpha1-antiprotease (582+/-86 vs 1178+/-148 ng/ml, P < 0.01) and elastase inhibitory capacity (EIC) (8.1+/-1.3 vs 17.7+/-1.9 micromol/ml, P < 0.01) were also significantly increased in the oldest age group. This cross-sectional investigation suggests that low-grade inflammation exists in the air spaces of many clinically normal, older individuals.