Factors affecting the interaction of asbestos fibres with mammalian cells: a study using cells in suspension

One of the earliest events in pathogenesis by mineral fibres must be an interaction between fibre and cell surfaces. Using a simple technique in which cells in suspension were incubated with fibres and adhesion monitored by separation on a density gradient it has been shown that such interactions occur through two distinct mechanisms. The first, a charge-mediated effect, occurs with positively charged fibres such as chrysotile asbestos. The second, with amphibole or glassy fibres, is mediated by fibronectin which first binds to the fibre. The bound protein then attaches to RGD receptors on the cell surface; calcium and magnesium ions are necessary for optimal adhesion. The RGD receptors bind to a tripeptide region on the protein and small peptides containing the RGD sequence block fibre-cell interaction. If the surface silanol groups on the fibre were chemically coupled to trialkylsilyl groups then interaction was slowed.