In aged humans and animals, lung injuries are generally more serious and prolonged. From a kinetic perspective, the authors thus assessed whether lung expression of proinflammatory cytokines were altered with age following intratracheal lipopolysaccharide (LPS) challenge in mice. Tumor necrosis factor-alpha, interleukin-1beta, macrophage inflammatory protein-1alpha, macrophage inflammatory protein-2, and keratinocyte-derived chemokine were significantly higher in 65-week-old mice along with sustained neutrophilia when compared to 11-week-old mice at 72 hours, but not at earlier time points. The authors concluded that the degree of LPS-induced neutrophilic inflammation and the expression of these cytokines differ with age at later phases of acute lung injury.