Binding of immunoglobulin and activation of complement by asbestos fibers

Asbestos fibers adsorbed IgG from whole human serum in amounts comparable to that taken up by crystals of calcium pyrophosphate or hydroxyapatite, but less than that adsorbed by crystals of monosodium urate monohydrate. Chrysotile asbestos was much more active in binding IgG than was amphibole asbestos. The electrophoretic mobility of adsorbed IgG was a function of the surface charge of the crystal studied. Negatively charged fibers adsorbed cationic IgG, and positively charged fibers adsorbed anionic IgG. Complement activation by asbestos, as judged by electrophoretic conversion of C3, was similar for all fiber types tested. Properdin factor B was also activated in the presence of asbestos. Activation of both properdin factor B and C3 was only partially inhibited by ethylene glycol tetraacetic acid, demonstrating that activation was occurring through both the classical and alternative pathways.