In vitro biologic responses to native and surface-modified asbestos.

A comparative study was made of in vitro biologic responses to native chrysotile, amosite, and crocidolite and corresponding asbestos fibers whose surfaces were modified by metal oxides. Interferon induction by influenza virus was depressed by approximately 50% by all native asbestos whereas corresponding surface modified asbestos minimally affected this nonspecific cellular defense mechanism. The release of the cytoplasmic enzyme, lactate dehydrogenase (LDH), and lysosomal enzymes, beta-N-acetylglucosaminidase (beta-NAG) and beta-glucuronidase (beta-Gluc), by rat alveolar macrophages after exposure to either native or surface-modified asbestos (which is indicative of membrane damage) was monitored. Although both native and surface-modified asbestos induced significant leakage of LDH, generally, lesser amounts of the enzyme were released as a result of exposure to the latter than to native asbestos. Whereas all forms of native asbestos caused significant release of beta-NAG and beta-Gluc, leakage of these enzymes from macrophages exposed to surface-modified asbestos was minimal. In contrast to native asbestos which induced irritation of cell membranes, as indicated by hemolysis of sheep erythrocytes, surface-modified asbestos exhibited minimal hemolytic activity. The findings indicate that surface modification of different asbestos by metal oxides generally lessened the adverse effect of the native mineral on the aforementioned biologic entities.