COMPARISON OF NEUTROPHIL CHEMOTACTIC FACTOR RELEASE BY HUMAN AND RABBIT ALVEOLAR MACROPHAGES IN RESPONSE TO TANNIN EXPOSURE

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. Mos t of the effects of tannin on alveolar macrophages (AM phi) have been studied in rabbit AM phi. Therefore, we compared tannin-mediated in vi tro neutrophil chemotactic factor (NCF) secretion from normal human an d rabbit AM phi. For both species the NCF secretion from AM phi was de pendent on tannin dose and time of exposure. The NCF released was a li pid 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 phosphatid yl inositol membrane lipids. The NCF secreted was not leukotriene B-4 or platelet-activating factor. In conclusion, tannin mediates the rele ase of a so far undescribed NCF from resident AM phi in rabbits and hu man subjects that may contribute to the pathogenesis of the acute neut rophilic alveolitis associated with cotton dust inhalation. The simila rity of results obtained from human and rabbit cells supports the pert inence of using rabbit cells to study tannin-mediated effects.