Toxicity to endothelial cells mediated by cotton bract tannin. Potential contribution to the pathogenesis of byssinosis.

Byssinosis is an occupational disease of textile workers caused by exposure to the bract portion of the cotton plant in the form of mill dust. The authors established an in vitro cytotoxicity assay using 51Cr release to assess time- and dose-dependent toxicity of condensed tannin, a component of bracts, on porcine aortic and pulmonary arterial endothelial cells. Tannin produced dose-dependent toxicity to both types of endothelial cells; aortic endothelial cells were more sensitive than were endothelial cells from the pulmonary artery. Skin fibroblasts were relatively insensitive to tannin. Cytotoxicity was not immediate. Release of 51Cr was preceded by a several-hour period during which the endothelial cells underwent profound morphologic changes (as assessed by light and electron microscopy). Even brief exposure of endothelial cells to tannin produced later toxicity and morphologic changes. Condensed tannin causes time- and dose-dependent injury to endothelial cells in vitro at doses potentially achievable in vivo.