ABSTRACT
Bacterial endotoxins (lipopolysaccharides), important components of many organic dusts, are known to induce macrophages to produce the inflammatory mediators interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-alpha). To investigate the role of these mediators in the early inflammatory responses in the lung, guinea pigs were exposed to an aerosol of bacterial endotoxin. A bronchoalveolar lavage (BAL) was then performed, and TNF-alpha and IL-1 in lysed BAL cells and in the supernatants from BAL cell cultures were studied. The effect of single and repeated LPS inhalation exposures on the activities of TNF and IL-1 was studied, as was the effect of LPS added to the cell culture medium. A single inhalation exposure to LPS caused an increase in the TNF-alpha and IL-1 activities in cell lysate and in the cell culture supernatant. After a second inhalation exposure, cell-associated and extracellular TNF-alpha activity could not be detected, whereas IL-1 activity was markedly enhanced. IL-1 activity was increased when LPS was added to the cell culture medium with or without a prior inhalation exposure. In contrast, TNF-alpha activity was not affected after a second exposure.
