Comparison of neutrophil chemotactic factor release by human and rabbit alveolar macrophages in response to tannin...

It is essential to determine whether the results obtained from animal models actually reflect human disease processes. Tannin is a component of cotton dust that acts as a polyclonal cell activator in vitro. Most of the effects of tannin on alveolar macrophages (AM phi) have been studied in rabbit AM phi. Therefore, we compared tannin-mediated in vitro neutrophil chemotactic factor (NCF) secretion from normal human and rabbit AM phi. For both species the NCF secretion from AM phi was dependent on tannin dose and time of exposure. The NCF released was a lipid with a molecular weight of less than 800 daltons, suggesting that it may be a metabolite of arachidonic acid. Tannin stimulation of both human and rabbit AM phi resulted in the release of 90% unmetabolized arachidonic acid derived from both phosphatidyl choline and phosphatidyl inositol membrane lipids. The NCF secreted was not leukotriene B4 or platelet-activating factor. In conclusion, tannin mediates the release of a so far undescribed NCF from resident AM phi in rabbits and human subjects that may contribute to the pathogenesis of the acute neutrophilic alveolitis associated with cotton dust inhalation. The similarity of results obtained from human and rabbit cells supports the pertinence of using rabbit cells to study tannin-mediated effects.