Altered epithelial lining fluid parameters in old normal individuals

Pneumonia is a leading cause of morbidity and death in older patients, and immunosenescence is believed to contribute to their susceptibility. In order to investigate whether age-related changes occur on the epithelial surfaces of the lung, bronchoscopy and bronchoalveolar lavage (BAL) were performed without complication in 19 young (27.7 ± 4.2 yrs), 6 middle-aged (49.8 ± 3.5 yrs), and 8 old (74.1 ± 4.3 yrs) normal, nonsmoking subjects. BAL was performed by instilling and retrieving five 20 ml aliquots of normal saline into three sites. The returns from the first aliquots (the bronchial sample) were analyzed separately from the returns from the subsequent aliquots (the distal sample). Lavage fluid cellularity was characterized and IgA, IgG, and albumin were measured by ELISA. Lavage fluid returns were lower in the elderly group and correlated with spirometric parameters. Significantly elevated numbers of neutrophils were recovered by the bronchial sample fluid from the old group. In contrast, no consistent difference in macrophage recovery by either the bronchial or distal sample was noted. In both the bronchial and distal samples, IgG, but not IgA or albumin, was elevated in the group of old subjects. Alterations occurring in BAL fluid with aging may reflect changes in local host defenses.